I hope that works for people, if it doesn't here is the solution that worked for me:
1. Slowly uncheck the Pillars of Eternity DLCs on Steam DLC content list one by one, each time waiting several seconds for the DLC to go from "installed" to "not installed", Steam will download a small 0kb update every time.
2. Shutdown Steam.
3. Launch Steam and log in.
4. Go to your games library and right-click Pillars of Eternity, choose Properties. In the Properties menu go to the Local Files tab, click Verify Integrity of Game Cache, wait for it to go through the validation process of the