i've been having this problem since installing beta version (i have more details of the issue in another thread).
That was on android 5.0
However ever since upgraded to android 8.0 (oreo) the "offline" problem has gone away. been on oreo for about 2 weeks already and everytime all bulbs are "online". no issues since oreo!
to be clear, no "offline" problem before the recent app update (20-Nov) nor after the app update.
PS: i updated to oreo around 15-nov