Any song imported from the rekordbox xml with one or more stars is imported as 5 stars. My guess is because rekordbox stores each star as a value 51 in the xml, and not 0-5, the rating field is being parsed incorrectly. A 1 star rating has a value of 51, 2 is 102, 3 is 153, 4 is 204, and 5 is 255. Should be an easy fix.
Thank you for the report. This behavior has been confirmed.
I’ll pass this over to the dev team for investigation.