ZigBee Lights Offline Randomly. Cycle Power of Lights Fix them

openHAB 3 in Docker under ubuntu.
ZigBee + HUSBZB-1 + Ember EM35x Coordinator + sengled lights.
The things of the lights went offline randomly, tried disable/enable “Ember EM35x Coordinator” and the lights, they would go online for several seconds then went offline again.

Only cycling power to the LIGHTs fix them. But they do not stay online for ever.

There are several repeated warning in the log after it went offline:

[WARN ] [.core.thing.binding.BaseThingHandler] - Handler ZigBeeThingHandler of thing zigbee:device:f257c81010:b0ce1814030fc79c tried updating channel B0CE1814030FC79C_1_dimmer although the handler was already disposed.

Those lights were working normal under Wink-Hub.

Wonder what the cause is.