Blitzcrank Grab sticks enemy into turret

During a tower dive blitzcrank grabbed Ivern. Ivern should have had enough hp and shields to waltz out, but he became stuck to the turret and died.

This is the only time I've encountered this bug.

It may be linked to triggerseed. When Ivern gets grabbed into turret his triggerseed explodes. He has time to cast triggerseed one more time and appears able to walk for a brief second.