Illaoi tentacles from Test of Spirit don't show for max feast Battlecast Cho'Gath

I was fighting normal skin Illaoi last night as Battlecast Cho'Gath in top lane. Everything was fine for the beginning. If she managed to grab me with her E (Test of Spirit) and I went out of range, I'd get the indicators for the tentacles that spawned so I could dodge the slam. But when I got to max Feast stacks, then I stopped seeing the tentacles or their attack indicator until it actually slammed me making it much more difficult to dodge.