For the past few out-of-game weeks, my cow and chicken, who have won in the Animal Festival, would default pose in the entrance of their homes when I let the animals out for the day. They moved inside the barns, but still had no animation. Upon investigation, I realized that they had dinosaur costumes on and removing them fixed the problem. Putting the costume back on freezes them again.
Rate: any time I dress my cow or chicken
Platform: Steam
Version: 1.1b-1235
Input: controller
File:
#Winner animals don't animate in costume
dusk gust
Video
Note: I had taken the costume off before letting the animals out. The photo is how they appear when I let them out in costume.
sacred rivet
Hello @dusk gust! Thank you for bringing this to our attention. I'll relay this to the team for further investigation. 
dusk gust
Thank you! I don’t know if the animals get a medal after winning in the festival, but if they do, that’s my best guess as to the cause.