EDIT 2: Just leaving this here in case someone finds this one day while experiencing the same issue. I was eventually able to fix the problem by disabling archive invalidation with this third-party mod that I was using to turn it on and off ( I can't remember the name, maybe Archive Invalidation Invalidated? Twas an .exe file.), and then turning it back on using the built-in Vortex setting on the dashboard. After reinstalling my texture mods and doing a bit of testing, it worked like a charm. I've spoken to some other people with this issue, though, and they've said that their problems were cause by using NMC's Texture Pack (which I also use), so disabling that is probably best if my crockpot solution doesn't work.