I played the YOTB-event last friday (before the bugfix update) and unlocked almost every befaloo costume. Yesterday I played again and wanted to change the costume, but only a single one was unlocked - even the costume my beefalo was wearing at this moment was locked.
The unlocked costume wasn't the initial costume I had on friday:
- Friday: Dolled-Up Costume
- Sunday: Festive Costume
(I unlocked all costumes again, if something happens, I will give an update.)
Not sure, but maybe: