It's a design flaw of the program. There are murky historic restrictions prohibiting BB to mix 3/4 and 4/4 time bars, when a user wants to start out with 3/4 time. The usual workaround here is creating some 4/4 time first dummy bar and then mix time signatures ad lib. Not sure why medleys aren't allowed with 3/4 time throughout, though. That's more than a glitch and definitely needs attention by the program creators. Creating some one bar dummy song in 4/4 time up front would here be a more or less functional workaround. After the creation of the medley those 4/4 time bars may be deleted. The medley then starts out in 3/4 time ... with some botched count in, though.

Martin