Hmm, it should recognize, I don't think there is a setting that would change the ability to recognize a minor chord. It might depend on your playing style..are you using bar chords? have you tried playing a single strum major chord, ..see that it recognizes it, then transition to a minor in the same key do one strum and see if it recognizes the change. The WX is an early model and might just not have as good chord recognition..there may be a setting which only recognizes the root for accompaniment, so it would only play the major note accomp and not any minors, or maj7 etc..
hope this helps..I havent' used my WX for a long time..I moved up to the Genesys XP, a Roland BK7m and Ketron Audya