This isn't so a problem with PM, rather one of user error... however, it causes PM to lock up (I don't have enough patience to try to wait it out and end up force quitting)
Here's what happens:
Using Code Replacement... If I direct PM to search for a code in a Supp Category, but I've accidentally placed the code in the wrong field, PM 4.4.3 locks up when the code is missing. I.e. in Supp Cat 3 I place the code xyz and in the caption I write something that includes \{suppcat2}\.... however Supp Cat 2 is empty and PM locks when trying to apply the Stationery Pad.
Would it be possible to pop up a warning explaining the desired field is empty, or code not found, or task aborted, or "do you wish to abort?" or similar, rather than having to force quit? Yes, it's user error but it would beat having to start over.