I have had the same issue, especially if I have a lyric window open beside the main BIAB window. I usually will have the lyric window and the BIAB window split vertically on the screen with the lyric window taking about 1/3 of the screen and the BIAB window using the remaining 2/3 of the screen. As the song progresses and then reaches the end of the last line displayed in the chord window, BIAB won't shift the page properly and all I see is the new chord on top of the previous display but only as each current bar is played.
I have rebooted and the problem will correct itself for awhile then eventually it will revert back to this.


-Darren