This time,

In the mixer panel I select an instrument / real track and save it. I can see the chosen instrument stays yellow. Regen the project and I CAN see the top line says "regenerating" and the percentages. BUT if I hit play nothing happens, NOTHING plays.
I have to shut down BIAB , restart it, re open the project and it plays!! The instrument / Track is now Green.
What's going on here?

Frustrated of Purley.

Yellow means it is a "Midi" track. Green means it is a "Audio - Real Track". Other than that, not enough info to go on. At some point you may want to upload the file and give us the link so we can look for ourselves.

Dan

Thanks. Not sure how that affects the inability to play back anything though.

We need either more information of the song to really help or a copy of the song. You stated the track starts out as yellow and that means it is MIDI but after a reboot it turns to green, a RealTrack. I have never seen that happen. You can load the file into the free DropBox, https://www.dropbox.com/ and tell us the link so we can see it. Be sure to send the one with the yellow track.

Questions, did you have a MIDI track then replace it with a Realtrack? What was your workflow?

One of two things going on...
1) you don't know how to operate BIAB to play a file - If you send us the file we can confirm it plays or does not. If it does not play for us, then we will likely see why it does not and will fix it and return.
2) If it plays well at our end then you likely have a configuration problem with your drivers (Win and/or BIAB)
In that case, you have to detail out your configuration setup for both Midi and for Audio on your PC and in BIAB.

Without that, just like both Mario and I have said, you really have given us nothing to go on. Keep at it, we will get you up and running with a few passes of comments.

Dan