[GAMEPLAY] Enemy champions immune to Tahm's Devour even with 3 stacks

I have had multiple games now tonight where enemies become immune to being eaten by W. It is like the game does not even recognize they exist -- I get no "This unit cannot be devoured" message, no grab-misses like vs units with CC immunity, it just won't even try to eat them.

For example, I'm playing vs a Nasus. He goes all-in on me. I stack him up, stun him, back away, go back in, try to W him. Nothing. Cast Q, he gets stunned, so I try to W him again (thinking maybe it had been a visual bug where I saw 3 stacks of acquired taste that weren't really there), but nope, still cannot eat him. This happened multiple times to nasus in that game where he would become immune to my W. I thought maybe it had to do with his ult wearing off or some other status effect on him, but no clue. I've also had it happen to me before vs a Fiora where she would become immune to my W.

The immunity lasts a long time. I am not sure if it requires the stacks to fall off completely and be reapplied, or if it requires one or the other of us to die, but in every case where I become unable to eat a given champion, it seems to last for the entirety of our fight.

Also note that during this bug, I can still Q stun them, so it is not just some bug where they don't have 3 stacks. They are fully stacked, they just cannot be eaten with W.

Thanks for reading!