Don't know if this is new to 2010 or not, but was modifying a song I had already on disk that had no RTs by adding a bass part. Here is the setup:
Style: C_90BAL.STY (also tried =C_90BAL with same result)
Tempo: 65
RT selected: Bass/Electric/Country/Evn065 (I tried a different bass/electric of some sort with the same result)

What is happening appears to be related to having a 4/4 song with a Bar Setting for one bar at several points in the song making a 2/4 bar (2 beats), with a held chord (D) followed by a return to 4/4 via Bar Settings and a different chord. When playing all works until the bar following the hold. The bass doesn't change to the new chord (in this case a G) but plays the D bass. If all bars are 4/4, everything works as it should. MIDI bass works fine as well. A new bug or a known issue?

Liking 2010 very much so far although I have noticed a couple of anomalies with resizing the window and playing a song. Could be my setup - will do more testing before I think the insect word.

Thanks all