Aperture crashed. I restarted with no real distasters, just annoyances. Thumbnail views now disappear even on images I just worked with.
Some projects have thumbnails OK in Project view but none in Split View.
One project that was importing when my issue happened has some color noise thumbs tha, when queiered via "Show in Finder", report "External volume this was imported from is offline". Not true. Never took those volumes online.
Do I delete the "bad", unconnected files from this above project and re-import from a backup folder with "Do not import duplicates" ticked? Should that solve the missing file problem?
However, what's up with the vagaries of thumbnails dynamically disappearing? Whatever I do doesn't seem to re-create them.