This must be obvious, but it's driving me mad. Here's what happens:

Import a pile of pictures in a new project.
Go through them all rating the good ones (either using '/' or the number keys 1-5)
Apply a filter to only see (say) 1-* or better

So far, so good. Now I only see my picks and I can work on them.

Now when I quit Aperture, re-start and go back to this project, the filter is still there but it shows me NO images. If I change the filter to 'Show All' and look at an individual image it'll have the right rating, but the filter just doesn't seem to see it.

What's wrong? I've tried Googling to see if anyone else has this issue, but it's not the best set of search terms to try and look for.

Odd. Unsure what's going on... my filters and views based on star ratings work fine after Aperture restarts :-/

I'm pleased to say that the issue has gone away after blowing away from com.apple.aperture.plist preference file and the latest Aperture upgrade. I'm not sure which of these actions fixed things, but it's good.