Sometimes, I look at my tribe and it says: Error: You are not in a tribe.
That happened even though I was in a clan.
Who knows why this happened?
P.S.: This just happened days ago during me playing Transformice. Please fix!

Maybe it was a one off!

That might have happened due to community platform being unstable at that moment.
I had the same bug recently, but I know the platform had many issues, and that caused the bug to appear, re-logging/waiting a bit will help.