Hi Max,
I've consulted our developers, and here are the results:
1. We haven't faced such behavior yet. So, to help us reproduce it and find a solution faster, please provide us with additional information on your operating system (the total amount of RAM, your processor name, and so on). Any additional information on this problem is appreciated.
2. Also, it will be very helpful if we get a video demonstrating the problem. For instance, you can record the test execution and the general results. Make sure that the video contains the contents of the Picture panel (that contains the compared pictures) and an image showing the difference between the compared images (for this purpose, click the Comparison Mode button in the Picture panel).
If you don't want to share this video here on the forum, you can send it to our Support Team via the Contact Support web form.
Thanks.