after trading i'm stuck in act 2

I killed the final boss from the act but i didn't pass to the next act, i was trying to complete the ascent to power quest, then i found an good weapon on sale on the trade market, i was added to the party and made the deal but then i see i could make to the sanctum, and i tried but now i'm locked on act 2 because i can't progress to the first checkpoint on act 3, is there a way to fix this by myself? I'm sory English is not my first language

i fix it, i just restart the map on the checkpoint in traitors passage then the game reseted the progression.