I've just started using PM 4.5.3.2 on OS X Leopard, having used it without problems on Tiger for some time. Now I'm experiencing problems with the structured keywords panel.
The first time I use the panel - no problem. Here's an example:
On subsequent uses, however, tend to suffer from a number of problems:
* child items and synonyms are not displayed - only the top-level items are displayed - here's the same selection as above after this has happened:
* sometimes not even all of the top-level items are displayed, allow there are arrows indicating where they should be and that they have child items:
After this, PM seems to become unstable. I've had several crashes - something I never encountered under Tiger.