Hello - hope I can help.
I experienced this a few months back and I found the fix in the Addon Manager\texture folder in the rules_handling file. It'll show something like couatl.basecolor = white or something similar. I changed all the white options to couatl.basecolor = cool_grey and that has done the trick, although with Swissport would be suited to the Red option.
I just make a replacement rules_handling file and copy it over & amend with new handlers with each new update as I have my local airport handler edited too into the file.
Hope this works for you!