@dash and @BarryCarlyon
Thank you for taking your time to review and comment on my thread.
Did as you suggested, however the issue resolved itself when I decided to register mock up extension at dev.twitch portal (ht to @BarryCarlyon for zeroing on Auth header) rather than using the DevRig generated one.
PubSub was more than happy to accept the former.
Once again thank you for your time and Happy New Year,
Gex