For the record... I just spent 20 minutes trying to figure out why ANY image on a disk image I had mounted (read/write) would launch preview but then do nothing. Also dragging the jpeg to preview would not open it. It just ignored me, and left NO error messages anywhere I could find.
Rebuilding launch services database did not help.
I finally had a stroke of luck while troubleshooting... if I changed the "open with" for one of the images to Safari and then double clicked it, GATEKEEPER popped up saying I could not open this jpeg because it was from an unknown developer, AND telling me that "safari downloaded this disk image at xxx". (I made this disk image using disk utility) OK that's totally bizarre but would sort of explain the problem I'm experiencing.
Sierra generously removed the "open from anywhere" option, so I hacked that back on but it still didn't want to work. Further research found that the quarantine flag is stored as an xattr on files, or in this case, on the disk image file itself. ls -la@ didnt show any quarrantine flag on any of my disk images. Ok whatever, I'll nuke it anyway to see if anything changes.
in terminal: xattr -c (filename)
That strips all extended attributes. It also nuked the custom folder icon of the disk image. Whatever, I can fix that. I can now open images in preview from that disk image.
I'm getting really tired of fighting my operating system to get everyday tasks done.
