I just discovered something that may help.
Did Google search and came across a paper re no sound in BIAB.
I opened one of the DEMO songs in BIAB and it played OK through more than one chorus. The paper said that the virtual piano keyboard at top should show activity as the demo song plays. It did.

I next reopened that song that was not sounding at all and now it played normally BUT there was no activity on the virtual piano keyboard at top.

If I restart BIAB, my song has no sound and doesn't even start when pick PLAY - crashes.
If I restart BIAB, play the DEMO song, then open my song, it again plays normally (but still no activity on piano keyboard).

I don't know what all this means. (Nothing in paper about if keyboard not showing activity).