Many people seem to suffer from that issue; there seems to be another post on the forums aswell. It seems to be related to “Flail” weapons and it being on a character. Check if you have any “Favorite” characters on your warband that have the transmog of a flail weapon, warriors and paladins tend to have some of them for example (but I am sure there are others. Paladin has the legion transmog for example). Removing the Flail fixed the issue for a lot of us, worth a shot atleast! 