OK, seems like I was a bit premature in talking about success.
Shortly after the sensors “went off”, i.e. they went to status undefined and any changes are not shown in OH2 (in the MiHome app they do show the changes).
I tried everything I can think of, even, finally, deleting and re-installing OH2 more or less from scratch.
Any other ideas what to do? I have a trace file this time:
2017-12-30 23:41:33.050 [TRACE] [g.mihome.handler.XiaomiBridgeHandler] - Received message {“cmd”:“report”,“model”:“magnet”,“sid”:“158d0001586c18”,“short_id”:36159,“data”:“{"status":"open"}”}
2017-12-30 23:41:33.051 [TRACE] [g.mihome.handler.XiaomiBridgeHandler] - Updated “last time seen” for device 158d0001586c18
2017-12-30 23:41:33.053 [DEBUG] [home.handler.XiaomiDeviceBaseHandler] - Item got update: {“cmd”:“report”,“model”:“magnet”,“sid”:“158d0001586c18”,“short_id”:36159,“data”:“{"status":"open"}”}
2017-12-30 23:41:33.061 [DEBUG] [ler.XiaomiSensorBaseHandlerWithTimer] - Setting timer to 300s
2017-12-30 23:41:33.064 [TRACE] [.mihome.internal.socket.XiaomiSocket] - Data received and notified 1 listeners
2017-12-30 23:41:33.065 [TRACE] [.mihome.internal.socket.XiaomiSocket] - Thread Thread[Thread-695,5,main] waiting for data on port 9898
2017-12-30 23:41:33.785 [DEBUG] [.mihome.internal.socket.XiaomiSocket] - Received Datagram from 192.168.178.30:4321 on Port 9898
2017-12-30 23:41:33.786 [TRACE] [g.mihome.handler.XiaomiBridgeHandler] - Received message {“cmd”:“heartbeat”,“model”:“gateway”,“sid”:“286c0788ae6c”,“short_id”:“0”,“token”:“cCz0ZQKFGSc7DdcJ”,“data”:“{"ip":"192.168.178.30"}”}
2017-12-30 23:41:33.787 [TRACE] [g.mihome.handler.XiaomiBridgeHandler] - Updated “last time seen” for device 286c0788ae6c
2017-12-30 23:41:33.789 [DEBUG] [home.handler.XiaomiDeviceBaseHandler] - Item got update: {“cmd”:“heartbeat”,“model”:“gateway”,“sid”:“286c0788ae6c”,“short_id”:“0”,“token”:“cCz0ZQKFGSc7DdcJ”,“data”:“{"ip":"192.168.178.30"}”}
2017-12-30 23:41:33.791 [TRACE] [.mihome.internal.socket.XiaomiSocket] - Data received and notified 1 listeners
2017-12-30 23:41:33.792 [TRACE] [.mihome.internal.socket.XiaomiSocket] - Thread Thread[Thread-695,5,main] waiting for data on port 9898
2017-12-30 23:41:34.505 [DEBUG] [.mihome.internal.socket.XiaomiSocket] - Received Datagram from 192.168.178.30:4321 on Port 9898
2017-12-30 23:41:34.506 [TRACE] [g.mihome.handler.XiaomiBridgeHandler] - Received message {“cmd”:“report”,“model”:“magnet”,“sid”:“158d0001586c18”,“short_id”:36159,“data”:“{"status":"close"}”}
2017-12-30 23:41:34.507 [TRACE] [g.mihome.handler.XiaomiBridgeHandler] - Updated “last time seen” for device 158d0001586c18
2017-12-30 23:41:34.509 [DEBUG] [home.handler.XiaomiDeviceBaseHandler] - Item got update: {“cmd”:“report”,“model”:“magnet”,“sid”:“158d0001586c18”,“short_id”:36159,“data”:“{"status":"close"}”}
2017-12-30 23:41:34.520 [DEBUG] [ler.XiaomiSensorBaseHandlerWithTimer] - Cancelled running timer
2017-12-30 23:41:34.521 [TRACE] [.mihome.internal.socket.XiaomiSocket] - Data received and notified 1 listeners
2017-12-30 23:41:34.522 [TRACE] [.mihome.internal.socket.XiaomiSocket] - Thread Thread[Thread-695,5,main] waiting for data on port 9898
2017-12-30 23:41:35.735 [DEBUG] [.mihome.internal.socket.XiaomiSocket] - Received Datagram from 192.168.178.30:4321 on Port 9898
This is the part where I open and close the door. The status in OpenHab, however, remains undefined, although data seems to flow.