Hello,
I had a photo open and tried to apply lattice distortion ("Gitterverzerrung" in German). After I saw that nothing happens when I pressed the apply button, I clicked the close button for the image so I was back in the main screen from where I wanted to open another photo. Before the file open dialogue appeared, my Affinity Pro trial version just froze and CPU usage went up to 75 % (modern CPU, so quite a lot) and 500 MB RAM usage. After waiting up to 5 minutes, the program never responded again. I closed it with the closing button in the top right corner and that just worked instantly.
I suspect that the application was trying to apply the lattice distortion after the file has been closed and thus ended in some endless loop.
Best Regards