I'm just chiming in here not being able to read your choice of instruments on my tiny screen...

I know from using some Midi styles that this can be a problem when adding in a RealTrack. The one I recall was a Bossa style where the Midi bass played on the 1 and 3 of the last measure and the RealTrack played the final chord on 1.

I am aware that you are using all RealTracks but may want to look at your choice of instruments and make sure they are similar in feel and tempo. You may get weird results mixing an even feel with a swing.

Also, have you tried loading one of the predefined RealStyles and see what happens there. If all works fine, it may help you figure out what is happening for future reference.

R