Hi,
I would advise you to contact the theme author for support, since they will be able to solve your issue. This plugin is just a tool for theme authors to implement the one click demo import for their users. The content being imported is still theme specific, so we can’t help you here.
The issue could be in the theme content import files or in your hosting server setup. Do any images import? Go to the media section in wp-admin and check if there are any images there… If not, then it might be that your server does not allow connections to a different server to fetch the images… Or the theme content import file has outdated image URLs and that’s why the import never ends, because the images are being imported over and over again in each new AJAX call and they keep failing…
This is just some info for you or the theme author, so you can investigate further.
You can also contact your hosting company and ask them, if there are any PHP errors or warnings, that might help you find the issue.
Take care!