I have 6 zemismart RGBW downlights in the kitchen. All working fine until contractor work required power to be cut.
Now power is back on, all lights were greyed out and not available.Network did not stabilise itself, so deleted the greyed out lights and attempted to add them as new. I now have 1 working light, but the other 5 will not pair. Have powered on and off, extracted from ceiling and hard reset with button, restarted home assistant and conbee.
Nothing seems to work. All software and firmware up to date as far as I can see.
Sometimes you have to reset these lights with a 5x or more power cicle on - off until they start blinking.
Did you try that?
I think I have narrowed it down to interference from my WiFi router.
Over the weekend I will install a new router in a different location, and move the Home Assistant Blue to the opposite corner.
I will also try 5x power cycle!
Have tried everything. No joy.
Conbee in completely different part of the flat, as far away from the wifi router as I can get it.
Have reset gateway, put in pairing mode and it only finds one light out of 11 in the flat.
Reinstalled Phoscon Integration in Home Assistant, now get error message “Failed to set up: Could not authenticate”
Hit configure and get error message “Config flow could not be loaded: 500 Internal Server Error Server got itself in trouble”
Conbee is set to channel 25, 2.4GHz Wifi is set to channel 1, so there shouldn’t be interference.
Still waiting for some logs 
I know, but I’m working on an ipad and there seems no way of making the text in the deCONZ window of the Home Assistant app larger. I can barely read any of the text, which is making life more difficult than it should be.