Hecarim's devastating charge against maokai's twisted advance

Just played a game against a hecarim playing maokai. Everytime I twisted advanced him while he was devastating charging I would get rooted well away from him while he was able to hit the adc. true he might have gotten the hit off right while I was advancing... but shouldnt I be where he ends up not where he started his charge? It seems like I get rooted and he doesnt ( I know he gets rooted after the end of the charge) but I'm not on him and I cant peel for adc. Seems like a bug that should be fixed.