I play on steam.
I have all the Free DLC and a few of the other DLCs I own the first two games and am borrowing the third from my sister's game Library. When I boot up Total War Warhammer 3 it gives me access to all of her DLC but none of mine. It used to give me access to all of mine as well as her DLC until this last update with the 5.0/5.0.1 release.
I have
1: Verified the game Files.
2: Deleted The Launcher files and Verfied/reDL game files.
3: Downloaded the game and Started it on a completely different machine.
For example I can not play Vlad, or Isabella, Imrik, Alith Anar, Any Brettonian, My Chaos Warriors DLC. I can play her Skaven DLC and Her Ogre kingdoms DLC, Those are all the ones I tried checking out already that I know should be playable. I played A Vlad Campaign and an Alith Anar Campaign Last month before the 5.0 Update so I know I could play it back then.