I have read the Sticky “Theme Options – not saving changes [RESOLVED] [FIX]”
And made the recommended Edits
The solution is to increase your WP_MEMORY_LIMIT
I also deactivated all Plugins I was not using as this is a brand new install.
I change the BG color and text color, hit the save button and it shows as expected. Go to the Site and it’s back to white background and black text.