Re: PS4 Dragon Age Inquisition won't load save files
I ran into the same problem and got it to work. Here's what happened / what I did.
After backing up all my save data to the cloud, I installed a new HDD in my PS4. After reinstalling the game and updating (I had a physical copy of the game) I downloaded my saved data from the cloud. When I started the game and tried to continue where I left off or load a save I got the error mentioned in OP about not being able to load the save file because the game was installing even though the game was fully installed. After searching I tried reactivating my licenses through the settings -> PSN account management menu but this did not solve the problem even after restarting.
I deleted / reinstalled all my save data from the cloud and this did also not work. On a whim I went to the overview and checked my trophies for the game. When I did this, the game sort of synced my trophies (there was a progress bar that said something but it went by really quick). After going back into the game, everything worked properly and I was able to load my game.
It may be that the game doesn't think it's fully installed because the trophies have been synced. This worked for me, hopefully it will help others out there as well. Good luck.