After all these years, I learned something new. If you connect a secondary controller to an MPP, without a primary controller, it will fly just fine. However, no flight record is recorded in the Go4 app.
I do not have dual controllers for my M2P. Good to know.Same thing with the M2P/Z. Grrrr.
Plus there are two std controllers for the M2P/Z, the RC1A & RC1B, the RC1A will create a DAT file when it is the only controller or the Primary controller. The RC1B will NOT create a DAT file, full stop.
I don't know if you have an equivalent 'problem' with the MPP.