If you run mods in ATS and your Truck Configurator is all black in 1.27, it's likely Viper2's Pete 389. Here's the fix.

I have a ton of mods installed and I was pulling my hair out trying to find which one was causing this. It also affects the Truck Browser the same way.

Anyway, I narrowed it down to Viper2's Peterbilt 389, before discovering that Viper2 has released a hotfix (source) (direct link). EDIT: Steam Workshop version has now been updated. H/T to u/LaiLaiHei.

Happy Trucking!