When ratings are saved to the file as a tag, they're available to any program that wants to read the tag, just like the Artist tag or Title tag. At the point where they're saved correctly, and here they are, it's up to other programs to read from those tags.
Nothing more Musicbee could be expected to do.
FWIW GoneMad reads Rating tags just fine. If your player of choice doesn't support the tags you want to use, sounds like it's time to look for a new player.