Frostqueen's Claim extra stacks bug

Hello, I have noticed this bug a few times lately but just now figured out how to upload replay clips so here goes. This bug can be reproduced by just using the active from the full frostqueens item and while the cooldown is counting the stacks seem to not get used up when hitting people or objects with the auto attacks. I have a clip here showing me proc'ing the passive 7 times in a row on objects before the stacks were finally used up. I have done this on other champions and the value seems to be between 7-13. I don't know what the criteria is for the higher amounts. I had at this point in the game frost queen, sight stone, sorc boots, rylais, blasting wand.