It appears that if you "ignore" a user that started a thread, that thread is then hidden from your favorites.
I'm interested in the topic, just tired of the OP. I had to un-ignore to get the topic back in favorites.
My preference would be to allow threads by ignored users to show up. I don't see a setting for this.
I thought this was a bug, but as I type this I realize it may be working as intended... in which case this is a feature request
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Your browser/os information:
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Firefox/45.0 (this will help us make sense of your bug report)