Upfront does not save changes

Hi all,

I have a huge problem. After updating Upfront this morning all of a sudden it stopped saving changes to the Spirit theme. No matter what change I made, after I click "Save" it says "All Done". But when I exit the Upfront editor 1) I receive message from the browser that there are unsaved changes and whether I am sure I want to leave and 2) after I check the changes again they have not been saved and I see the old content/form.

I have tried with disabling all plugins but even with just WPMU Dashboard active I still receive the same result: no matter what I change to the Spirit Theme it does not saves.

I have tried switching themes, but the result is the same.

Please HELP ASAP since my client's site does not look pretty at all https://jocotours.com

Thanks a lot!
Vladimir