Not sure if this is just not implemented yet but I am only able to access/purchase class and backgrounds from the Players Guide or the Advanced Players Guide. Searching anything else returns a blank unlock button which returns an undefined popup (with add to cart). (See images)
Note, I did not previously have access to the Advanced PG, and did purchase it through the character creator interface, so it is not just unpurchased books that there is no access to.
Tested with Gunner and Thaumaturge as well as multiple backgrounds.
Hi biblioblade, you’re right that we don’t have all of the sources set up yet.
Here’s a quick reference table we shared last week, as to what percentage of options we had worked through internally.
Thanks for letting us know about the APG purchase, it’s good to know that’s working! For the short term, we only have options from the Core Rulebook, the Advanced Player’s Guide, and Gamemastery Guide available while we continue to roll out content from other sources as we work through them. 
Got it. Thanks.
I’m seeing a lot of content from Lost Omens books as well (Ancestry Guide and Character Guide in particular)l - is that expected, or is that a bug?