Affinity Photo thumbnails not showing

[Grant@personalsecurity.us]

I have a question about thumbnail images. In any view, digikam shows thumbnails for RAW, TIFF, and JPG image files. However, even though Affinity Photo has an embedded JPG preview in their file (which the Mac Finder shows, for instance) and “aphoto” is one of the recognized file formats in the Preferences>Views>Mime types>Additional file extensions panel, those files have a placeholder graphic instead of a thumbnail.

Is this a known limitation, or is there something I’ve missed in my configuration?

(P.S.: Using latest versions of digikam and Affinity Photo; MacOS 12.7.1)