Hey! If you guys are finding problems with log-in with Facebook account, I Suggest you go to webnovel's help center (in the app, you can just enter without login and find it)
Then click on the "account problems" and then find the "Online customer service".
Just right above the the 'send' buttom you'll find an 'Live agent' where you can talk to a real person about the problem.
Tell them that you can't log in using Facebook anymore and you are afraid to lose your account. You just have to tell them your profile username and they will tell you wat to do.
They were really efficient, but don't leave the conversation, otherwise it'll restart. I did it last night and took about ten minutes to solve the problem