Upfront Themes not saving changes

I keep making changes to this test page and the changes are not saving. It keeps reverting back to what it had shown before. I have tried looking up solutions but I don't have any additional plugins installed and cannot see the issue. It was working fine until Friday afternoon when I got a few changes from my customer.
I'd like to finish this off to take it live but I can't use this theme plugin if it won't save consistently.
Can you see what the issue might be?
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