I am playing CS:GO through a family shared library. I can play online casual matches and bot matches however I can't play competitive matches through my account. However, if I login to my brother's account (he's the one who bought the game), I can play competitive matches. Why doesn't this work?
I believe only offline play is supported for a shared copy of CS:GO.
Trying to find an official statement from Valve, but the link above has users talking about this exact situation.