I had a visual bug yesterday. I'm not sure how I did it Just found out how to replicate it- if you level up a dragon and quickly switch to another dragon while the feeding meter's animation is still going, it will make the feeding meter "stuck"(doesn't do anything with the feeding, could still feed the dragon).

The meter animation was on the right and not on the feeding meter itself.

The simple way to fix it is to exit the feeding screen and enter again