For green label, for instance, default settings in English are
Label: Personal
Read: Green, Approved
Write: Green
In browser mode, everything works as expected, green label is described as Personal and Green is written to XMP-xmp:Label, when writing is enabled.
In Compare mode - with two pictures being compared side by side - in the context menu, green label becomes Work, blue is Personal, red is Uncolored, and there is another Uncolored at the bottom - like on my first screenshot.
Custom settings for the second screenshot are simple:
Label: Green
Read: Green
Write: Green,
etc. for all colours.
Obviously, in compare mode, green becomes Yellow etc.
So I can reproduce this with untouched default settings or custom settings.