There are headlight mod glitches and unsaveable advanced paint in the current patch (images below).
Note that I have successfully verified the integrity of game files.
Some of the headlight mods remained buggy (grey cross-sections originally, then I changed textures on some headlights and it became transparent).
Tested Mods: Twongi Headlights, L5 the Useless, Shinyodd R30, L5 the Mucho Very and one of the Classic Headlights Pack (oval bezel, dual round headlights with central partition).
1970-08 to 1970-10 colors are different when I saved it on car, for example, 1970-08 is like Desert Yellow, 1970-09 is like Butter Yellow and 1970-10 is like Bright Yellow.
1970-08 to 1970-10 colors are identically matte black when I saved it on Global, however, it only occurred when I used Advanced Paint Mode, as Basic Paint Mode saves different colors normally.
Edit 1: Headlight Mods are now working, but the Advanced Paint Mode is still not working as of Patch 7, as it couldn’t save my customized colors using that mode, such as cloth are saved as matte paint instead.