[android app] "Gadgetbridge plugin is not installed on bangle.js"

The 'Gadgetbridge plugin not installed' error happens when some code running on the watch produces an error. It's possible that some app installed on your Bangle is producing errors.

You could try setting debug = log in settings -> utils, then using it for a bit and connecting with the Web IDE to see if there's anything in a file called log.txt that would give you some ideas what was going on