I just flew 2.37 downloaded through the latest planner.
Compass issues and Mission Planner
I think I figured out my compass issue with 2.36/2.37. When I used the mission planner to setup the quad after download, I got bad compass behavior when entering "-0.666666" for my declination. The compass is offset by about 90 degrees and the compass test returns large negative numbers.
I went into the CLI and entered: "declination -0.666666" and the compass started working ok with proper heading and compass test working. I diagnosed this by loading 2.24 for other reasons and noticing my compass not working right there also. So I got confused by the cli using fractional degrees while the planner converts from degrees minutes to fractional degrees.
I noticed that the sonar output now is being averaged and on the bench returned reasonable numbers on the MB1200. When I flew 2.37, the alt hold worked a little better, but it still did not hold well. The quad generally rose until I canceled alt hold. My logs show fairly bad sonar data.
I loaded 2.24 (was working with my hardware) just to see how the sonar looked and if alt hold worked and it didn't work on this version either showing noisy sonar data - but not averaged.
My conclusion is that something about my sonar mount location or wiring is just bad and needs to be fixed. I'll spend some time tearing apart my sonar mount and trying some radically different locations on the frame to see if I can clean up the return signal. I don't think my quad is currently a reasonable test case for Alt Hold until I diagnose and fix the sonar noisy data.
Attached is my 2.37 flight log.