If your masks are showing up as black, this tool will not fix that. Update or uninstall your shader mods instead.
This tool fixes the material_configs for any custom (i.e. non-vanilla) masks made prior to Update 243, so that they can support the new customization options.
To use this, find the folder that contains your custom masks (typically "PAYDAY 2/assets/mod_overrides"), extract "custom_mask_material_fixer.exe" to the same folder, and run it. It will automatically detect and fix any custom mask material_configs.
Source code available in the "src" folder if you're paranoid or would prefer to run it manually. The exe was created with PyInstaller.