Build Buy CC Thumbnails won't generate

So I hadn't played the game in 3-4 months and I updated everything and removed mods that were broken, deleted all the cache files and last exceptions, updated Nvidia drivers, buuutt all my custom content in build mode that doesn't have a custom thumbnail is invisible. Like the game isn't generating a new thumbnail for it. It's incredibly annoying and some have the dreaded big question mark when I click on them. I don't understand what's happening. Everything was showing up fine last time I played. I batch fixed the thumbnails to DX11 in S4S and that did not solve the problem either. Help?