It gets even better.
I recreated the entire file from scratch, using a newly created text file, resetting all the screen colors and fonts, retiming the lyrics, and exporting new .bin files (demo and karaoke versions). I saved the KHPro file a couple times while working on it to see if I could reopen it, which I could. Once I had finished the demo version I saved the KHPro file again. I closed KHPro without saving again after swapping the music track to the karaoke version because I typically save only the demo version.
I couldn't reopen the newly created KHPro file... same "earlier version" message. So I checked a few other KHPro 5.00 files to see if they have the same problem. Nope, they seem to be okay.
