PSD thumbnails turn black in finder

[Charls]

Reviewing psd files in finder. They momentarily appear as a normal image then are replaced by an Affinity Photo thumbnail then turn black all within 3 to 4 seconds. The files are on an external hd and I do not want to transfer a couple hundred images to make a selection of 3 dozen.

[DWright]

This issue of images showing black in finder has been reported several times to Apple and the solution from their support team is to reduce the size of the thumbnail image, if a file format has been linked to an Affinity app you will see the default app icon rather than a black thumbnail.