Thanks Jim,
I do have BiaB installed on the Mac, latest version, that's why I was wondering if there might be a compatibility issue between the original songs done on 2018 on Windows and trying to open them in the DAW in Apple 2020, although, as I think I said, the songs will open in the main version. That's what got me flummoxed, you'd think the two versions (on Mac) would work in tandem.

I've emailed chat but the time difference between Australia and the States means playing email tennis between the time zones.