Since the patch went live some staircases seem to have issues, usually with the top step having a lip/wall that stops your character as they are running up them, you can get past them by jumping or moving to the side as you slide along the invisible object.
Happened in Banished Cells 1 after killing one of the mini bosses, another one is in one of the stages of DSA as you are heading to the portal.
Did someone accidentally lift the whole map instead of moving a candlestick???