Thanks for taking time to respond to my question. My Items are created using text based files. For this exercise/example to demonstrate the issue I am using a dimmer for fireplace lighting. The Item declaration is the same for both OH2 and OH3.
OH 2 Item:
Dimmer v2A35C71FireplaceLoadLevel "Fireplace Lighting" <screen> (Group_HabPanel_Dashboard, PubItems_CMD, gLighting, gFamilyRoom) ["WallSwitch"]
OH3 Item:
Dimmer v2A35C71FireplaceLoadLevel "Fireplace Lighting" <screen> (Group_HabPanel_Dashboard, PubItems_CMD, gLighting, gFamilyRoom) ["WallSwitch"]
When Issuing a command from OH2 to adjust the Fireplace Light I see these events in the OH2.events log Turning it OFF from 73% state then turning on to 73% state.
2020-11-29 12:33:10.909 [vent.ItemStateChangedEvent] - v2A35C71FireplaceLoadLevel changed from 73 to 0
2020-11-29 12:33:20.923 [vent.ItemStateChangedEvent] - v2A35C71FireplaceLoadLevel changed from 0 to 73
The corresponding OH2.log entry is
2020-11-29 12:33:10.901 [TRACE] [sy.internal.IsyWebSocketSubscription] - Parsing message: [<?xml version="1.0"?><Event seqnum="260" sid="uuid:1462"><control>DOF</control><action>0</action><node>2A 35 C7 1</node><eventInfo></eventInfo></Event>]
2020-11-29 12:33:10.902 [DEBUG] [sy.internal.IsyWebSocketSubscription] - Node '2A 35 C7 1' got control message 'DOF' action '0'
2020-11-29 12:33:10.903 [DEBUG] [binding.isy.handler.IsyBridgeHandler] - onModelChanged called, control: DOF, action: 0, var event: null
2020-11-29 12:33:10.903 [TRACE] [binding.isy.handler.IsyBridgeHandler] - find thing handler for address: 2A 35 C7 1
2020-11-29 12:33:10.904 [TRACE] [binding.isy.handler.IsyBridgeHandler] - Find thing for address: 2A 35 C7
2020-11-29 12:33:10.904 [TRACE] [binding.isy.handler.IsyBridgeHandler] - address: 2A 35 C7
2020-11-29 12:33:10.904 [DEBUG] [binding.isy.handler.IsyDeviceHandler] - handleUpdate called, control: DOF , action: 0 , node:2A 35 C7 1
2020-11-29 12:33:10.905 [TRACE] [sy.internal.IsyWebSocketSubscription] - Parsing message: [<?xml version="1.0"?><Event seqnum="261" sid="uuid:1462"><control>ST</control><action>0</action><node>2A 35 C7 1</node><eventInfo></eventInfo></Event>]
2020-11-29 12:33:10.906 [DEBUG] [sy.internal.IsyWebSocketSubscription] - Node '2A 35 C7 1' got control message 'ST' action '0'
2020-11-29 12:33:10.906 [DEBUG] [binding.isy.handler.IsyBridgeHandler] - onModelChanged called, control: ST, action: 0, var event: null
2020-11-29 12:33:10.907 [TRACE] [binding.isy.handler.IsyBridgeHandler] - find thing handler for address: 2A 35 C7 1
2020-11-29 12:33:10.907 [TRACE] [binding.isy.handler.IsyBridgeHandler] - Find thing for address: 2A 35 C7
2020-11-29 12:33:10.908 [TRACE] [binding.isy.handler.IsyBridgeHandler] - address: 2A 35 C7
2020-11-29 12:33:10.908 [DEBUG] [binding.isy.handler.IsyDeviceHandler] - handleUpdate called, control: ST , action: 0 , node:2A 35 C7 1
2020-11-29 12:33:10.909 [TRACE] [sy.internal.IsyWebSocketSubscription] - Parsing message: [<?xml version="1.0"?><Event seqnum="262" sid="uuid:1462"><control>_1</control><action>3</action><node></node><eventInfo>[ 2A 35 C7 1] DOF 0</eventInfo></Event>]
2020-11-29 12:33:10.909 [DEBUG] [pdb.internal.MapDBPersistenceService] - store called for v2A35C71FireplaceLoadLevel
2020-11-29 12:33:10.909 [DEBUG] [sy.internal.IsyWebSocketSubscription] - Node 'n/a' got control message '_1' action '3'
2020-11-29 12:33:10.910 [TRACE] [sy.internal.IsyWebSocketSubscription] - Parsing message: [<?xml version="1.0"?><Event seqnum="263" sid="uuid:1462"><control>_1</control><action>3</action><node></node><eventInfo>[ 2A 35 C7 1] ST 0</eventInfo></Event>]
2020-11-29 12:33:10.911 [DEBUG] [pdb.internal.MapDBPersistenceService] - Stored 'v2A35C71FireplaceLoadLevel' with state '0' in mapdb database
2020-11-29 12:33:10.911 [DEBUG] [sy.internal.IsyWebSocketSubscription] - Node 'n/a' got control message '_1' action '3'
2020-11-29 12:33:20.915 [TRACE] [sy.internal.IsyWebSocketSubscription] - Parsing message: [<?xml version="1.0"?><Event seqnum="264" sid="uuid:1462"><control>DON</control><action>0</action><node>2A 35 C7 1</node><eventInfo></eventInfo></Event>]
2020-11-29 12:33:20.917 [DEBUG] [sy.internal.IsyWebSocketSubscription] - Node '2A 35 C7 1' got control message 'DON' action '0'
2020-11-29 12:33:20.917 [DEBUG] [binding.isy.handler.IsyBridgeHandler] - onModelChanged called, control: DON, action: 0, var event: null
2020-11-29 12:33:20.918 [TRACE] [binding.isy.handler.IsyBridgeHandler] - find thing handler for address: 2A 35 C7 1
2020-11-29 12:33:20.918 [TRACE] [binding.isy.handler.IsyBridgeHandler] - Find thing for address: 2A 35 C7
2020-11-29 12:33:20.918 [TRACE] [binding.isy.handler.IsyBridgeHandler] - address: 2A 35 C7
2020-11-29 12:33:20.919 [DEBUG] [binding.isy.handler.IsyDeviceHandler] - handleUpdate called, control: DON , action: 0 , node:2A 35 C7 1
2020-11-29 12:33:20.919 [TRACE] [sy.internal.IsyWebSocketSubscription] - Parsing message: [<?xml version="1.0"?><Event seqnum="265" sid="uuid:1462"><control>ST</control><action>188</action><node>2A 35 C7 1</node><eventInfo></eventInfo></Event>]
2020-11-29 12:33:20.920 [DEBUG] [sy.internal.IsyWebSocketSubscription] - Node '2A 35 C7 1' got control message 'ST' action '188'
2020-11-29 12:33:20.920 [DEBUG] [binding.isy.handler.IsyBridgeHandler] - onModelChanged called, control: ST, action: 188, var event: null
2020-11-29 12:33:20.921 [TRACE] [binding.isy.handler.IsyBridgeHandler] - find thing handler for address: 2A 35 C7 1
2020-11-29 12:33:20.921 [TRACE] [binding.isy.handler.IsyBridgeHandler] - Find thing for address: 2A 35 C7
2020-11-29 12:33:20.921 [TRACE] [binding.isy.handler.IsyBridgeHandler] - address: 2A 35 C7
2020-11-29 12:33:20.921 [DEBUG] [binding.isy.handler.IsyDeviceHandler] - handleUpdate called, control: ST , action: 188 , node:2A 35 C7 1
2020-11-29 12:33:20.922 [TRACE] [sy.internal.IsyWebSocketSubscription] - Parsing message: [<?xml version="1.0"?><Event seqnum="266" sid="uuid:1462"><control>_1</control><action>3</action><node></node><eventInfo>[ 2A 35 C7 1] DON 0</eventInfo></Event>]
2020-11-29 12:33:20.922 [DEBUG] [sy.internal.IsyWebSocketSubscription] - Node 'n/a' got control message '_1' action '3'
2020-11-29 12:33:20.923 [DEBUG] [pdb.internal.MapDBPersistenceService] - store called for v2A35C71FireplaceLoadLevel
2020-11-29 12:33:20.923 [TRACE] [sy.internal.IsyWebSocketSubscription] - Parsing message: [<?xml version="1.0"?><Event seqnum="267" sid="uuid:1462"><control>_1</control><action>3</action><node></node><eventInfo>[ 2A 35 C7 1] ST 188</eventInfo></Event>]
2020-11-29 12:33:20.924 [DEBUG] [sy.internal.IsyWebSocketSubscription] - Node 'n/a' got control message '_1' action '3'
2020-11-29 12:33:20.924 [DEBUG] [pdb.internal.MapDBPersistenceService] - Stored 'v2A35C71FireplaceLoadLevel' with state '73' in mapdb database
The OH3.events.log I’m not seeing an entry it is set to INFO just like the OH2
OH3.Log is
020-11-29 12:33:10.909 [TRACE] [nternal.rest.RemoteopenhabRestClient] - Received event name message date {"topic":"smarthome/items/v2A35C71FireplaceLoadLevel/state","payload":"{\"type\":\"OnOff\",\"value\":\"OFF\"}","type":"ItemStateEvent"}
2020-11-29 12:33:10.910 [DEBUG] [l.handler.RemoteopenhabBridgeHandler] - Unexpected value type OnOff for item v2A35C71FireplaceLoadLevel
2020-11-29 12:33:10.910 [TRACE] [nternal.rest.RemoteopenhabRestClient] - Received event name message date {"topic":"smarthome/items/v2A35C71FireplaceLoadLevel/statechanged","payload":"{\"type\":\"Percent\",\"value\":\"0\",\"oldType\":\"Percent\",\"oldValue\":\"73\"}","type":"ItemStateChangedEvent"}
2020-11-29 12:33:10.910 [TRACE] [nternal.rest.RemoteopenhabRestClient] - Ignored event type ItemStateChangedEvent for topic smarthome/items/v2A35C71FireplaceLoadLevel/statechanged
2020-11-29 12:33:20.923 [TRACE] [nternal.rest.RemoteopenhabRestClient] - Received event name message date {"topic":"smarthome/items/v2A35C71FireplaceLoadLevel/state","payload":"{\"type\":\"Percent\",\"value\":\"73\"}","type":"ItemStateEvent"}
2020-11-29 12:33:20.924 [DEBUG] [l.handler.RemoteopenhabBridgeHandler] - updateState remoteopenhab:server:openhab25x:v2A35C71FireplaceLoadLevel with 73
2020-11-29 12:33:20.924 [TRACE] [internal.events.ThreadedEventHandler] - inspect event: org.osgi.service.event.Event [topic=openhab] {topic=openhab/items/v2A35C71FireplaceLoadLevel/state, source=remoteopenhab:server:openhab25x:v2A35C71FireplaceLoadLevel, type=ItemStateEvent, payload={"type":"Percent","value":"73"}, timestamp=1606671200924}
2020-11-29 12:33:20.924 [TRACE] [nternal.rest.RemoteopenhabRestClient] - Received event name message date {"topic":"smarthome/items/v2A35C71FireplaceLoadLevel/statechanged","payload":"{\"type\":\"Percent\",\"value\":\"73\",\"oldType\":\"Percent\",\"oldValue\":\"0\"}","type":"ItemStateChangedEvent"}
2020-11-29 12:33:20.924 [TRACE] [nternal.rest.RemoteopenhabRestClient] - Ignored event type ItemStateChangedEvent for topic smarthome/items/v2A35C71FireplaceLoadLevel/statechanged
2020-11-29 12:33:20.925 [TRACE] [ab.core.internal.items.ExpireManager] - Received '73' for item v2A35C71FireplaceLoadLevel
Just to put a final point on this, if I change the state of the Fireplace Light from OH3 I do get an event in the OH3events.log as shown below, and the light dims as expected.
2020-11-29 12:58:47.127 [ome.event.ItemCommandEvent] - Item 'v2A35C71FireplaceLoadLevel' received command 20
2020-11-29 12:58:47.156 [vent.ItemStateChangedEvent] - Item 'v2A35C71FireplaceLoadLevel' changed from 73 to 20
Thanks again for taking a look a this.