Ah, I found the issue! I had one mod that should have only added a few items to the game. It did add items to the game, but it also deleted a lot of them… somehow.
One Tap Truncheons is broken.
Removing that mod specifically and then re-validating the files twice fixed the issue. Re-validating files only once (which is what I tried at first) didn’t work. Twice worked.
Thank you for bearing with me and for the help!