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.
2. Insert the custom CSS code to change that color.
There is no any issue in the footer area itself… you can’t have both footer background color and footer background image set at once… if you set footer image background than background color will be set as transparent by current code.
What do you want to achieve with footer area exactly ?