I finally figured out today why it wouldn't work.
I didn't mention this before and didn't think it was an issue but when I was working on the files it was being opened on an external drive attached via USB. What I didn't realize was that the way Mac handles files is differently than PC. Mac can read NTFS but can't write to NTFS. So the drive was formatted as NTFS so it could read everything in PM fine. But when the tags were added, it wasn't adding whatever bits of info to the photo to denote it had been tagged because, again, Mac can't write to NTFS... of course w/o the help of something like Tuxera NTFS which solves the problem.
Now everything works and tags save as they should. I just wanted to make sure if someone else has this problem they'll know better.
Thanks!