OK... I HAVE SOLVED IT!

The audio driver in RB was set to Windows Sound, so I changed it to MME and now the metering works.

The problem with Helix Native VST2 not working was to do with an update of Native that I installed but did not tick the option to instal the VST2 dll. Normally this is VST3, which doesn't work in BIAB and RB.

Basically the software previous version was installed and working but the new update removed the graphical applet from BIAB an RB but the reference name was still showing in the RB VST list.
Very confusing to understand why it wouldn't load.

Thanks for your suggestions!