I eventually solved the problem - or rather partially. I suspected that there was something amiss with the image database. As my syncing tests progressed, I found that the number of blank events on the iPad doubled each time. I was also noticing that some of these events were getting thumbnails, with the collection of associated images when I tapped on them being totally different.
The database was, I concluded, corrupted. It was a case of either restoring the iPad, and NOT restoring from a backup (and risking losing all my apps’ settings), or finding a way to reset the database. I managed to find instructions for the latter here:
http://www.iphoneincanada.ca/how-to/how ... in-itunes/There is a Mac application that exposes the iOS device as a volume on your computer, it was a case of using this to delete the corrupted database files. The iPad then rebuilt the database when I opened the Photos app. None of my synced iTunes images were there (as expected), but all of the screen shots I had taken and thought I had lost were there.
Syncing from iTunes is still a problem. For example, if I tell it to sync only projects from the last 12 months, it seems to select pretty much every project going back to 2004. So I’ve manual selected the projects I want to sync to help save on space on the iPad.
So corrupted database problem solved. iTunes is buggy and not reading my Aperture library properly. Ho hum.