Hi Redweb,
I also met your situation in my environment(9.1.0000.4834).
I tried to add Opportunity Sale Process entity to site map both for Sales and Marketing App with XrmToolBox,
opened Marketing App in App designer to confirm whether the Opportunity Sales Process has been added,
and confirmed the process Primary Entity is actually the Opportunity.
but all attemps got same result as you described.
Then I found no elements were generated when I opened developer tool to detect BPF element in Marketing App in same form,
while relevant contents has been generated in Sales.
In my opinion, I thought it may be a bug or product design.
Hope this could helps.
Regards,
Clofly
