HITL PIXHAWK does not reset automatically after upload

[bravepaulo]

Describe the bug
After uploading the code in PIXHAWK 2.4.8 using QT creator, the board does not reset automatically and launch a warning telling that it was not possible to reset the board.

To Reproduce
Steps to reproduce the behavior:

1. Build the code in QT creator and run it to upload PX4_FMU-V3
2. Check that the erasing and uploading phases are ok
3. After uploading, the automatic reset is not done
4. See a warning about the impossibility of resetting the board
   5, After, if you do a manual reset, the UI LED on the board is off all the time
   6, The drone will arm modes but will disarm after some time even in flight (already reported: bug HITL disarm after takeoff FMU V3 #15417 )

Expected behavior
After uploading the code in PIXHAWK it was expected that an automatic reset would occur and the UI LED would blink in green or blue.

Drone (please complete the following information):

• PIXHAWK 2.4.8
• QT creator 4.12.0. QT based on 5.14.2

[stale]

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