Singed Poison Trail toggles off for no reason (not OOM)

I was fighting a Lissandra top and about 20-30 times throughout the game, my poison trail would toggle off for no reason. I had lots of mana so that wasn't it, and I wasn't pressing Q to toggle it off accidentally. I tried to test it on bots but couldn't get the bug to happen. It may be specific to Liss+Singed.

Edit: Just tried a custom with Singed vs Lissandra. Couldn't replicate the bug. Very confused.