After almost losing my sanity, I reviewed my old modlist on version 1.5.97 and downloaded several fixes and SKSE plugins. I also added a combat mod, Valhalla Combat (I don’t know why I did that at the time). After activating everything and playing, the bug didn’t appear in 1 hour and 50 minutes of gameplay. I have no idea which mod fixed the bug (so far). There weren’t any missing requirements from the list I mentioned earlier, but anyway, I’ll recover some of my sanity by finishing my list.
mods i added: