Thanks for testing that out again, in a very precise way.
The bug is now on the list of issues to be resolved. Thanks for your patience. For now 4.0.7 is the best solution for you.
Thanks for the report. As @amilcarlucas says this is the 2nd report of this issue (the other is here).
My understanding is that the issue is specific to this hardware and the workaround is that the autopilot must be powered on before the transmitter is turned on.
" the workaround is that the autopilot must be powered on before the transmitter is turned on"
Very clever and the workaround worked well all of the way up to the Flight Modes setup. No matter what I tried there weren’t any Flight Mode Options for me to select in any of the six windows? The Flight Mode windows were all blank and none of the scroll down buttons did anything.
Did you configure a FRAME_CLASS?
And update to latest Beta Mission Planner from the Help screen.
Configuring the FRAME_CLASS is the easiest thing to do and I swear I did it but I didn’t and now everything works, Great Call!
All of the SETUP steps worked properly and the quad flew well.
The workaround, “autopilot must be powered on before the transmitter is turned on” violates RC 101: Transmitter is always turned on first and turned off last. My question is should I live with the workaround or is the old 4.0.7 installation better for safety until the issue is resolved?
You guys have been terrific : )
It’s on odd consequence to have the Flight Modes not available if it’s not set and far from an obvious solution but seen it before 
Cool you got it going!
@dwiener see my replay on the other similar topic:
if you can try the same things and let me know that would be great
Same here I’m using expresslrs 2.0 hm ep2 receiver i do tested with serial port 4 and 5 but nothing happened on radio calibration tab , is it normal ?
Yes then what will be next step
Thank you 
@rmackay9 , @dkemxr , @amilcarlucas , @xfacta , @tridge
No it is not normal, check your connections, and test what happens when you power the flight controller before powering the RC receiver.
Tridge,
I’m using the RCIN port on the PX4mini.
I changed the BRD_SER4_RTSCTS setting from 2 to 0 and wrote the change to the mini. I checked to see that it actually got written.
The problem persists. The Radio Calibration displays in SETUP on Mission Planner will only respond to transmitter stick adjustments if I power the PX4mini on before I turn the transmitterr on.
My connection is ok , after check on serial port 2 , telemetry port 2 but no luck
I’ve found the bug and have put a link to the fix and a workaround here:
Here is a link to a PH4-mini binary that has Tridge’s fix applied. If someone could give it a try (just a bench test) and confirm it resolves the problem that would be greatly appreciated!
By the way, this is Copter-4.2.0-DEV so this hasn’t gone through beta testing yet so I wouldn’t recommend actually flying it (although it is probably fine).
Success!
I cannot reproduce any of the symptoms that I documented earlier. I installed Copter-4.2.0-DEV and I no longer have to apply the workaround, “autopilot must be powered on before the transmitter is turned on”. All of the SETUP functions work as expected. I took your advice and bench tested only, I did not attempt to fly.
Thanks, your persistence is greatly appreciated : )
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Tridge
I installed 4.1.2 and set SERIAL4_OPTIONS to 9 and the bug that I’ve been documenting with Radio Calibration is gone.
Thank you!
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