Blitzcrank grab going through sivir shield

Well I wish I had been recording but, I was playing sivir-braum into a blitzcrank-ashe lane and as blitzcrank does, he went to grab me, and as sivir does, I spellshielded. Now my spellshield went through because I had the animation pop of the shield eating the grab, and I gained mana back, but i still got displaced and cc'd. How does this even happen??? The whole point of picking sivir into blitz is to spellshield his grabs. I'm going to try to replicate it but idk how long it'll be till I face another blitzcrank as sivir. And no, ashe did not pop the shield with some move of hers. I thought maybe blitzcrank's passive lightning may have popped the shield, but alas, after a little research, his passive doesn't pop the spellshield. So I am very upset that I lost another dam game because of some bug. Last time it was Hecarim's ult and devastating charge not being blocked by spellshield. Some days, I just wonder if I should even upgrade the ability at this rate =_=. Hope this gets fixed. Thanks :)