Customize theme changes don’t get applied

I use Flatsome theme.
When I try to change anything in the ” customize ” or ” advanced options “page of flatsome it doesn’t work. I preview it and can see the change taking place then I hit ” Publish ” and it turns into ” published “. but when I refresh the page everything goes back to how it was. No change happens. Although the UX builder works perfectly. I tried the default ” Twenty two “theme and the changes worked well. I disabled all the plugins and it didn’t work either. I increase the php memory to 265 MB and it didn’t work. I downgraded wordpress to lower versions and it also didn’t work. What can I DO?
I use the last version of both flatsome and wordpress.
Thank you