Hello,stoffl!
I just tested these options on our test sites and I did not encounter the problem you are describing.
It’s most likely you have a conflict with some of the plugins you have activated, so I suggest you check the plugins first.
Deactivate ALL plugins temporarily to see if this resolves the problem.
If this works, re-activate them individually (one-by-one) to find the problematic plugin(s).
If that doesn’t help you, you have two options:
1. Give us the WP login credentials in the private reply , so we can check this directly on your website.
or
2. Insert the custom CSS code to change that color.
Best Regards