Invisible Toby

[Murder of Crows]

Recently started playing the game again and ran into this bug. I vaguely remember this from last time, but I can't remember how--or if--I fixed it. NPCs randomly become transparent, not invisible: you can see them barely. I run at high level graphics (not as high as my graphics card allows, but MTAP is a memory hog and crashes if I use ultra). I verified file integrity and was told no problems found. I started a new game. Toby was still transparent. Suggestions?

ETA: Reloading the game didn't fix the problem. I believe the invisibility is in the save file somehow? Anyway, I DL-ed my first mod--NPC textures--and Toby is again visible. Not sure what happened the first time.