Well...
It turns out that for some reason using WAS setting on my laptop is not a good idea if I want to use BIAB.

The only way it output sound is I give it sole priority which is very strange.

I am better off using the existing XR-18 ASIO Driver, as I use Helix Native through Gig Performer.

I tested it again, having GP, BIAB, Reaper, iTunes and YouTube, all at the same time! No issue with this ASIO Driver sharing audio sources.

I still don't understand why BIAB is having this anomaly with WAS. No problem if used with Realband or other software.

I did uninstall Asio4all rebooted Windows, changed the settings in BIAB to WAS, closed it, rebooted windows again still no change. I admit defeat and give up!

The reason I wanted to try WAS, was because when I ticked the settings for outputting MIDI sound in the Tutor window.

If I'm not mistaken, the previous version of BIAB was outputting MIDI sound. Now, the only way it will do that is if I copy the track to either the Melody or the Soloist track. That's strange, because if I click on the fretboard while the song is playing, I can hear Midi sound!

Maybe this is another bug?