I tried to edit in Photoshop by selecting an image in an album, but still cannot recreate the problem - the quasi master has been created correctly. What format have you set for your external editor? Mine is set to export to the external editor as tiff. The original master is a jpeg, the quasimaster a tiff. Both share the same filename, but have a different extension.
Perhaps an update to Aperture 3.2.4 will solve the problem for you. The Aperture 3.2.4 upgrade is supposed to improve the data exchange with external editor.
I just updated to 3.2.4, have done some digging, and think I might be on to something. Here's what's happening now:
For images never before edited in PS, Aperture is now created a quasimaster. In my sample, I had a NEF original and now have a TIFF stacked with it. If I then take that TIFF into PS to do additional edit - no additional preview/version shows up.
It seems that images that had a previous PS edit (both before and after update), no quasimaster is created when going into PS for second or third time. But, then, if I manually create a duplicate version of the image, Aperture creates a quasimaster of THAT duplicate version. I then have three versions showing when done.
To answer your questions, I originate with either NEF or JPG images...usually the former...and I configured external edit to be TIFF. I also generally flatten image before returning to Aperture.
it seems that images that had a previous PS edit (both before and after update), no quasimaster is created when going into PS for second or third time.
Great - that explains a lot - that is exactly as it is supposed to be: consecutive edits in the external editor will apply to the same quasimaster, thankfully, for the high quality quasimasters reqire a lot of disk space
I also generally flatten image before returning to Aperture.
That will lose you your layers, but Aperture cannot display them anyway.