Tangmo, sorry bump in to your thread.
Noel said something, I thought I would ask my question here instead of opening another thread. Maybe it will help you to troubleshoot too, depending if this was done previously...

Noel, if you are reading this. Can you please answer to the best of your knowledge? I had some issues too with 2020 smile I am wondering, if I revert to 2019, will it recognize all new 2020 RT's or the 2020 has some sort of database that new RT's can't live without?

Thank you,
Misha.