Don't know if it's just me, but the bass track also has a mandolin on it. Other styles that use the same bass real track don't seem to be affected. BIAB 2023 build 1013.

Normal : Medley track.

This old-time happy-dance RealStyle has a bluegrass sound and features a total of six instruments. Two background soloists are panned hard to the left and right, a mandolin and a fiddle. Both play steady-sixteenth melodies. Rhythm instruments follow the traditional boom-chicka bluegrass rhythm, and include banjo, mandolin, and acoustic guitar. Acoustic bass alternates between the root and fifth on the beat. No drums are used in this style. Note that there is a medley on the bass track that also includes a rhythm mandolin

Style is _TONFRO.STY (To And Fro Old Time Dance Sextet)

RealTracks in song: 3495:Bass, Acoustic, OldTimeHappyDance Ev16 125
RealTracks in style: 3378:Mandolin, BackgroundSoloist OldTimeHappyDance Ev16 125
RealTracks in style: 3373:Banjo Guitar, Rhythm OldTimeHappyDanceAndy Ev16 125
RealTracks in style: 3410:Guitar, Acoustic, Rhythm OldTimeHappyDance Ev16 125
RealTracks in style: 3383:Fiddle, BackgroundSoloist OldTimeHappyDance Ev16 12

Thank you. I did not realize that.