I bought the source book bundle and had access to all the sources, able to look up races, creatures, and spells. But while attempting to look up a creature I had previously searched, it said that I needed to purchase the source book again. I took screenshots of the creature while I had access to the book, and while looking at what I had access to, I lost almost all of the source books I had purchased. After going to one of my test characters that used a races from one of the books it miraculously "restored" that book.

Follow this link and make sure your Account Entitlements are in sync: (https://www.dndbeyond.com/account/marketplace).

They are currently in sync and I still do not have access to the previous books I purchased. It is still saying that I do not own them.

Then you must have accidentally logged in under a different login method (Which izards, Google, Apple, Twitch). Log out and try the other methods.