I have the same problem of AJAX problem when importing the demo files. I have then deactivated the non-related plugins.
However, when I went back to the base import page, there is only seeing the button “activate base version”, how can I re-import the files to solve the AJAX problem?
Please deactivate all the plugins not related to the theme and switch the parent theme, check the issue, if the problem remains, leave the plugins not activated and provide the site admin access to the private area