Thanks for getting back to me. I must have missed that they needed to be labeled Winner, Winner alt, etc... If you select the color class "[Adobe Lightroom]" from the PM drop down I thought the label names it populates were the correct LR names but turns out they are not. They have to be named Winner, etc
What you are saying should definitely not be the case. Lightroom uses color class fields named "Red", "Yellow", "Blue", "Green", and "Purple". It should definitely not be recognizing "Winner" as those were just Photo Mechanic's old labels. Your Preferences panel should look like my attached screenshot.
Are there XMP files for these files that you are adding color classes to? Open the XMP file and look for a line that starts with "xmp:Label" and let us know what it says after that, and what color class that image appears as in Photo Mechanic in Lightroom.