TFT shrink bugging out

In TFT a player had shrink on two characters, but shrink was bugging out, read on forums that the shrinks overwrite each other and bug out but was happening even with only one shrink (the other died, so even having 2 on your team causes bug).

What happens is for a split second they shrink and their health bar goes down, but instantly they regain that health and level. He sold one guy with it and it started working normally... but couldn't use the item of course.

However later in that same game bug returned, even though he only had one guy with shrink. Seemed to be related to them being level 3.