Ok thanks. I might switch to the test version as it doesn't seem to have many bugs with it

I'm not sure honestly, I think both should work. The reason for vehicle needing additive shader is just for the canopy to have semi transparent result. If the original one is not working, you will only not seeing the canopy part but shouldn't crack the game. The reason I'm using test version is that it seems to be more optimized .

Do I have to use the test version of additive shader for some of the mods, or will the regular version work just as well?