I'm not really sure if this is supposed to happen.
I was just chasing 
with Final Hour and Tumble, but when I hit my third silver bolts, nothing happened. I saw her mana bar and she didn't regain any mana. The spell shield did nothing.
it doesnt proc her spellshield because her silver bolts and tumble are autoattack enhancers. they dont work on sivir they instead work on the character vayne to give her more strength. since it doesnt actually affect sivir the spellshield cant proc.
Spell shouldn't block vayne tumble or her silver bolts. So when you're saying "nothing happened when you procced your third silver bolts and nothin happened" it should have proccced the extra damage and spell shield should have done nothing and remained on (for its duration)
