Ok, here's some progress-
I thought I'd run the compatibility modes before, but figured before I posted to that effect I'd give it another try to be sure. I started out by trying Windows 7 compatibility mode. There was change- the control engines would still not create or save correctly. When I closed the program, the system popped up a Program Compatibility Troubleshooter, which suggested what you mentioned- Windows XP (Service Pack 3). I applied it and tested that, and lo and behold, it now works as it's supposed to- I can create and use control engines in PAC Control. I then tested this also in PAC Terminal- in XP SP3 mode, it's working.
Now comes the really interesting part - in the interests of checking everything, I went back and unchecked the compatiblity mode, so it's back to native Windows 8. Now it works fine, even without compatibility mode. I did find that engines created while the program was in compatibility mode can't be deleted while out of the mode, and vice-versa. It would appear that the two modes overlap somewhere, but can't modify one another.
After deleting every control engine created with both programs, and clearing compatibility mode, both programs still operate well, and allow creation of and use of control engines. I'm going to theorize here that the program is unable to create a key group correctly in Windows 8, and that by using compatibility mode, the group was initialized, and is retained even if all the engines are deleted.
I was going to offer to allow your engineers to access my machine remotely, but now it's working, so it may not be of any use. If it would still be, please let me know and we'll work out a remote access.