I enabled the settings-per-character option, and copied my WTF folder to my other PC. All settings are correct except for on my main.
I found that there is actually no LunaUnitFrames.lua in my main's savedvariables folder, while there is for all my other characters. I tried copying the one from the shared variables, but that gave the same result as well.
Where the hell are the settings for my main character on my main PC then? I'm very confused.