FrameMaker 2020 with Mif2Go - How to get it to work after upgrading FM?

I had Mif2Go working with FrameMaker 2017 to create PDF files. I upgraded to FrameMaker 2020 and the process is broken. Does anyone know how to get FrameMaker 2020 to work with Mif2Go after an upgrade?

I use the following path to try to set up Mif2Go (entered in a command window run as Administrator):

"C:\Program Files\Adobe\Adobe FrameMaker 2020\FrameMaker.exe" -progid:FrameMaker.M2G -auto

This launches FM2020. Continuing in the same command window, when I try to convert a file, the following error message displays:

runfm Ver. 4.0, Build 005

This ID is not registered for FrameMaker: FrameMaker.M2G

You must first set up FrameMaker with -progid:FrameMaker.M2G

If I instead try to convert a file using a .bat file, a command window opens for a couple of seconds, then disappears, with no output or message.

I see info about the registry keys in the Mif2Go help file, but cannot figure out how to fix it.

Thanks.