I have been using Affinity photo Beta test version 1.7.0.209, when I export finished files to TIFF, the thumbnail image is corrupted , looks like something from a Hi Pass filter mid process screen, or some weird blend mode result. When I try to open the TIFF in AF Photo or ant thing else I get a weird pink rectangle, same shape as the photo canvass. AF Photo tries to open as a Raw File.
I have flattened the image and even rasterized it to no avail. This is on around 90% of my work, occasionally I get one that works. I want to archive all my processed images as TIFF to save on disc space.