HL2 Achievements Between Two Accounts

[Morality_Leach]

I've got 2 Steam accounts. One that's been VAC banned since about 5 years ago, and it's got HL2 purchased on it. I'm trying to transition between accounts, and just bought HL2 on THIS account. When I fired her up to play, all of my achievement progress from my first account shows up, and now I'm completely unable to earn achievements for HL2 on THIS account.

I've already uninstalled/reinstalled and that hasn't worked out for me. Anybody have any ideas?

Much appreciated!