Have you gone through the regular setup, including RC calibration? If so, maybe try CLI setup/erase /reset to clean your EEPROM settings and try again.
For sure radio calibration is needed as 2.7.3 erased eeprom. I had other strange behavior and radio calibration fixed that.
I'm going to propose some solution to Planner to address such cases.
With the new firmware versions, the motor control was reduced (
This produces a big loss of power!
You can look at the graph below:
Red = input receiver
6 = other color out motors
How to regain power???