Tan lines aren't working properly

Please tell me I'm not the only one with this problem? (I think the screenshot will speak of itself)

One of my sims will always get the same tan as the other one, who sunbathed first (usually). I initially thought it might be a mod-issue. But since removing them all (as u can see from the second screenshot) the problem still persists. Both the fem sim who had a previous tan, didn't get hers changed to the new one. And the male sim, did not have a tan at all previously and now got her old tan. HELP! This has to be a bug right?