I'm using Plane fw 3.8.0beta4 and MP latest beta 43.2 I think, I'll check when I get home. I only have 4 motors for testing. according to octa quad motor layout motors 1,2,3,and 7 can be tested. 5 motors are missing.
If possible it would be great if MP associated the motors with an output pin to ease diagnosis. since the abcd method is somewhat opaque