I've reported MC-45714 which has a lot more details. I've experimented a lot, but nothing's worked. I've found that it happens in the Desert and Savannah (where it doesn't precipitate), but not in the Plains. I think whatever fix was supposed to prevent them from running around when it's raining elsewhere has instead made them CONSTANTLY run around. There are more details in my report, it's just rather long to put in a comment.
I've reported MC-45714 which has a lot more details. I've experimented a lot, but nothing's worked. I've found that it happens in the Desert and Savannah (where it doesn't precipitate), but not in the Plains. I think whatever fix was supposed to prevent them from running around when it's raining elsewhere has instead made them CONSTANTLY run around. There are more details in my report, it's just rather long to put in a comment.