"Restore from URL" not working after update to WP 4.4

Hi everybody,

after I updated to WordPress 4.4 on my test website I wanted to do a “Restore from URL” which always worked like a charme before…but this time it did not work. It was showing me the being busy wheel as usual, after It was finished I got no message of successful restore or similar just a grey site and on the left still the dashboard…so I checked my site and everything was still the same – no restore happened.
The file size is 815 Mb.

Is this because of the previous update to WP 4.4 or what could be the reason? Before it always worked without problems.

Thanks for your help/sugestions. – energetic

https://www.ads-software.com/plugins/wp-clone-by-wp-academy/