Cannot "Open with..."

Right-clicking on a disk image with .hdv extension and selecting "Open with Clemens" brings up a message: Document could not be opened. Clemens IIGS cannot open files in the "Apple ][ hard disk image" format.
Same message with .2mg extension.
When I mount these disks and then boot the slot they both work fine.

Mac Mini M1, Monterey 12.7.4

Looking good otherwise. Interface is excellent.