Ideas
On June 10th, 2025 I found out that the Item Mortimer's Secret Bookcase from the Discover University Expansion Pack does not appear in my game, either in build mode or live mode.
The item is available in build mode, however, when I select it and drag to place it the item does not show up. It's basically invisible. It shows a shadow on the floor where it is supposed to be, if I hover my mouse over where I placed it I can still interact with it in live mode but it is invisible. This is the only item that does that.
I repaired my game at least 15 times since then, to no avail. As of today, on August 2nd, 2025, my game is up to date with the latest patches, still no bookcase. I even deleted the localthumbcache.package file, still not fixed. I don't have any mods installed.