I had upgraded to Catalina...
I had Toast 17, but after the upgrade 17 would not even launch, it crashed without even opening.. so I spent $100 and upgraded to Toast 18.
This at least runs, and lets me "Encode" the video up until it tries to actually burn a BD, or even tries to write an image file.
Comes up with error: Couldn't complete the last command because of a Mac OS Error. Result Code = -1310