I see them changing in HABApp_events, and in openhab.log. I had set the sleep interval between changing the state to 2s and 1s before the last post (it complained about a long running script both times). I just tried with .1s and same result (as expected).
[2021-04-11 13:17:07,638] [ HABApp.EventBus] INFO | g3ChronosOffWhenBright: <GroupItemStateChangedEvent name: g3ChronosOffWhenBright, value: OFF, old_value: ON>
[2021-04-11 13:17:55,805] [ HABApp.EventBus.openhab] DEBUG | {'topic': 'openhab/items/g3ChronosOffWhenBright/command', 'payload': '{"type":"OnOff","value":"ON"}', 'type': 'ItemCommandEvent'}
[2021-04-11 13:17:55,805] [ HABApp.EventBus] INFO | g3ChronosOffWhenBright: <ItemCommandEvent name: g3ChronosOffWhenBright, value: ON>
[2021-04-11 13:17:55,823] [ HABApp.EventBus.openhab] DEBUG | {'topic': 'openhab/items/g3ChronosOffWhenBright/V_Lights_KitchenSink/statechanged', 'payload': '{"type":"OnOff","value":"ON","oldType":"OnOff","oldValue":"OFF"}', 'type': 'GroupItemStateChangedEvent'}
[2021-04-11 13:17:55,825] [ HABApp.EventBus] INFO | g3ChronosOffWhenBright: <GroupItemStateChangedEvent name: g3ChronosOffWhenBright, value: ON, old_value: OFF>
[2021-04-11 13:18:38,205] [ HABApp.EventBus.openhab] DEBUG | {'topic': 'openhab/items/g3ChronosOffWhenBright/command', 'payload': '{"type":"OnOff","value":"OFF"}', 'type': 'ItemCommandEvent'}
[2021-04-11 13:18:38,205] [ HABApp.EventBus] INFO | g3ChronosOffWhenBright: <ItemCommandEvent name: g3ChronosOffWhenBright, value: OFF>
[2021-04-11 13:18:38,224] [ HABApp.EventBus.openhab] DEBUG | {'topic': 'openhab/items/g3ChronosOffWhenBright/V_Lights_KitchenSink/statechanged', 'payload': '{"type":"OnOff","value":"OFF","oldType":"OnOff","oldValue":"ON"}', 'type': 'GroupItemStateChangedEvent'}
[2021-04-11 13:18:38,224] [ HABApp.EventBus] INFO | g3ChronosOffWhenBright: <GroupItemStateChangedEvent name: g3ChronosOffWhenBright, value: OFF, old_value: ON>
[2021-04-11 13:18:38,286] [ HABApp.EventBus.openhab] DEBUG | {'topic': 'openhab/items/g3ChronosOffWhenBright/command', 'payload': '{"type":"OnOff","value":"ON"}', 'type': 'ItemCommandEvent'}
[2021-04-11 13:18:38,286] [ HABApp.EventBus] INFO | g3ChronosOffWhenBright: <ItemCommandEvent name: g3ChronosOffWhenBright, value: ON>
[2021-04-11 13:18:38,339] [ HABApp.EventBus.openhab] DEBUG | {'topic': 'openhab/items/g3ChronosOffWhenBright/V_Lights_KitchenSink/statechanged', 'payload': '{"type":"OnOff","value":"ON","oldType":"OnOff","oldValue":"OFF"}', 'type': 'GroupItemStateChangedEvent'}
[2021-04-11 13:18:38,339] [ HABApp.EventBus] INFO | g3ChronosOffWhenBright: <GroupItemStateChangedEvent name: g3ChronosOffWhenBright, value: ON, old_value: OFF>
I can just never successfully read the group value or get_value(). It always comes back as OFF.