LMAO DUDE THAT IS REALLY WEIRD! I'm investigating now!
EDIT:
Okay soo I did notice you need the event:
mario detector NOT moving
-Set Mario animation "Default" (or your stopped animation)
-Play Current Animation
As for the shrinking sprite....no idea! Hopefully someone can explain what's up...it's really weird!
Geggeegeggege wish I could help! )