Mathcad Prime 9: Legacy Converter Fails

Migrated my Mathcad Prime 9 to a new Windows 11 PC, moved license to new Host ID, etc.  Prime 9 seems to work as usual.  But the Legacy Converter always fails and aborts - no message as to why.  The Mathcad Converter folder is present with what appears all the .dll's and the  mccnv.exe  executable.  

Something else I need to do to bring this back to life?