Even though the X-52 Pro "sees" my old X-52 profiles, it will load them but the commands will not appear. And yes, the files extension is .pr0 according to the programming software update that changed them from the old .dat file extension.

What I did not realize was that even though the commands did not load back into their respective buttons, if I went to that button in the programming software and clicked on the far-right arrow looking icon, I got a list of available commands and guess what? There they all were! Sure, I have to manually go to each key in the software and choose the command, but at least it saves me some time by not having to look at the in-game control menu again and figure out what is what.

Here is a link to the video that explains it better than I can. Note that it should work for any Saitek controller to any other Saitek controller: