In the Windows version of BIAB, under "Print Options" (when in Leadsheet mode), there's a selection called "Whole Song" that needs to be active. Could it be this?
You are correct Noel, the Mac version has that same preference. For some reason I think the default value is "First Chorus", and I have had it default back to that on occasion.
I don't remember if it was from running updates, or I actually did reset defaults to factory settings, but yes that preference can change on you without realizing it.