Today, I exited BigPicture to go back to my normal Board view and watched in surprise as all my cards that didn't have due dates filled in with the same due date (Aug 5, 2 days ago).
I'm not sure BigPicture is the problem though, because a few weeks ago, I was just adding cards to a board and they were automatically filling in with a due date of two days prior. (Cards already on the board did not change.) I would then open the card, remove the due date, close, and a couple of seconds later the same due date would be back. I just ignored it and eventually it stopped.
Any suggestions? My Trello setup isn't too complex yet, I'm not opposed to removing all powerups and rules, but I don't think that would help since this problem has only happened twice in a month.
Details:
I did have BigPicture installed both instances, as well as some other powerups. But I don't have any powerups or rules designed to set due dates. I have a rule that reads {yeardaynumber}, but it wasn't enabled on the board in the latest event. I have a rule that uses "regex:/.*(Importance|Urgency|Time).*/" in case that matters (those three items are custom fields). I was using firefox in both situations, which is what I always use.