Okay, after updating RB to V3, I was able to open your file without any problems. All the chords seem correct beginning with the G Am Dm Em progression starting in bar 1 with two lead in bars. I also scrolled to the last bar (bar 337) and saw that the last chord is a C in bar 322 (which is actually the same as bar 324 counting the two lead in bars) with 17 empty bars after that, three of which were from the XML file from MuseScore. So, RB added 14 more bars at the end. No big deal.
So, then I checked and saw that there were indeed four tracks to play, the first a blue (midi) track of the melody and three more RealTracks. When I clicked on Play, the tracks played fine. Then I jumped ahead to bar 240 in the Chords window to check those chords, and they all looked correct with a Dm chord in bar 238, no chords in bars 239-243, and an Am chord in bar 244. Next, I decided to play this section beginning at bar 238. When I did, bars 241-243 sounded a little strange. So, I turned off the drums and bass guitar and played only the piano and melody. Bars 241-243 still sounded strange. So, I switched over to MuseScore and brought up the piano keyboard so that I could figure out which note the piano was playing in RB for bar 241. After some experimentation, I was able to determine that RB had changed the chord at bar 241 to a C chord and didn't change the chord again until it reached the Am chord in bar 244.
To summarize, the erroneous chord change has still occurred in the file you created, Silvertones. For me to test if a glitch would exist at the 240/241 bar boundary, I would have to insert a Dm chord into bar 241 and regenerate the tracks. But this issue is secondary to the erroneous chord change at bar 241. If RB would remember that there was a Dm chord in bar 238, there wouldn't be any need for me to insert a Dm chord into bar 241 and run the risk of a possible glitch occurring there. Besides, I shouldn't have to do this. RB's algorithm should be smart enough to do this for me without actually showing a Dm chord in that bar.