It's there in Vanilla BTS and it's not a bug, it's how it works. You are asked to vote because at least one of your cities has Confucianism, so you have the right to vote (you are a voting member and not a full member). And if you don't like the proposal, you can defy it and it won't pass. You only get the angry penalty in those cities which have Confucianism, so it's not so terrible. But if you let the resolution pass, even if you've voted agains it, it's obvious that other civs which are target of that resolution will hate you a little more. Moreover, you could switch to intolerant to remove confucianism from your cities: then you won't have this problem anymore.
Edit: LOL, Joseph now you beat me every time!