Just got a reply from Waves tech support.
 
This fixed it for me!!! 
 

Thank you for contacting Waves Tech-Support.
 
Please try refreshing your Waves Preferences & Caches folder -
 

1. Quit all running audio applications.
2. Press the [Win Key] + [R], type in: %appdata% and hit: OK. 
3. Delete the Waves Audio folder.
4. Launch your DAW again and check to see if the issue has been resolved.

 

BINGO!

That did it!!!

Yes all good.  Except in my case the next time I launched Waves Central it told me I needed to update Scheps Omni Channel again.  So I did.  Just to see.  But then I got back to the problem again. i.e. plugin not working.  I then deleted the Waves Audio Folder again as per instructions above and bingo all working fine again.  I launched Waves Central again though (expecting to see Omni Channel needed updating to which I would have not obviously) I was told there were no updates. 

Jeff Evans
Yes all good.  Except in my case the next time I launched Waves Central it told me I needed to update Scheps Omni Channel again.  So I did.  Just to see.  But then I got back to the problem again. i.e. plugin not working.  I then deleted the Waves Audio Folder again as per instructions above and bingo all working fine again.  I launched Waves Central again though (expecting to see Omni Channel needed updating to which I would have not obviously) I was told there were no updates. 

Interesting!
 
And yes, confirmed...
 
Flushing twice is necessary to completely clear this mess up. 
 
 

Thanks for everyone's help here. I think it must have got them working on it too over the weekend. I am happy as I am about to mix rather large job and at last I can use it!  It is a great plugin.

Great that you guys have it fixed. For those of us who have studiously avoided updating Waves Central thanks to this thread, is it safe to do so? Think I'll keep my head down for a few days yet.

Marshall
Great that you guys have it fixed. For those of us who have studiously avoided updating Waves Central thanks to this thread, is it safe to do so? Think I'll keep my head down for a few days yet.

I think it is safe to proceed, but you will probably still need to apply the corrective actions described above.  There is apparently something about the current update that is conflicting with the existing Waves Preferences and Caches folders.  No new updates have been issued to correct this yet!
 
If you are not in a hurry to get the update, it may pay to wait.

Si bueno, you da hombre!

Marshall
Great that you guys have it fixed. For those of us who have studiously avoided updating Waves Central thanks to this thread, is it safe to do so? Think I'll keep my head down for a few days yet.

As of today I just done the update, and there were no issues, Studio One, REAPER (didn't bother trying SONAR though) Scheps Omni works fine.