Since we updated to PHP 7, File uploader with Post Image is not working

Hello!

Until now your plugin worked very well! Thanks!
In the days we changed to PHP 7 (here is a phpinfo: https://bidf.hu/phpinf.php). Since than the File uploader with Post Image is not working. When I try to fill out a form, and I try to upload a file, and I click Submit, the ajax spinner does appear next to the Submit button, but it will ‘load’ forever. It works, if you do not upload an image. Here is a test form for you:
https://bidf.hu/test/

Cheers: Kolos

The page I need help with: [log in to see the link]