Thanks for playing! Glad you like it.
For this inventory bug, are you getting it when accessing the stash through the actual on-map stash, when opening your inventory normally, or both?
There’s no wiki at the moment. Advanced Knowledge is a category that includes Forbidden Knowledge and Arcane Revelations. I’ve had some questions about that so I do need to make that clearer in game.
Sources of Advanced Knowledge
Forbidden Knowledge can be gained from Tomes of Forbidden Knowledge, which can sometimes be found in cursed locations. Arcane Revelations can be gained from successfully assisting with the rituals on top of wizard towers, or from stealing the book in the center of the ritual circle at the top of wizard towers.