Mouse Leave animation inconsistency

I’m trying to figure out why some variant animation simply doesn’t work on mouseleave.
Here is an example. Exact same properties. Left Mouseleave is working. Right doesn’t:

Copy and pasting it to this sandbox project made my left button work properly. But sometimes it just doesn’t. It’s quite frustrating on my working project because i’m not able to tell if it’s simply me or a bug.

(also, the “while hovering” function don’t work either)

Does anyone experience the same issues? thanks !