As mentioned before, it would be nice to see .afphoto thumb images in PM.
Other software does this.
Perhaps you could ask them.
If Affinity provides documentation - at least enough to support extracting a thumbnail, we could support it. I'm going to mark this as something we will not implement, but if they change their mind, we'll happily revisit.
That thread link starts in 2016.
But does that explain why ACDsee, NeoFinder and Photo Supreme (IDimager), to name three, have no problem displaying afphoto thumb images and Photo Mechanic can't.
Yes, and it continues into this year. I can't speak to how other products have done this. Our team has determined that this is beyond our scope at this time.