Sounds like a motor issue or something happening with the gear drives.
Turn each prop by hand and see if one is maybe slightly harder to turn than the other.
My guess is either something is binding or its just a bad motor in general..i would guess the one motor that stops is probably quite hot compared to the others...If you cant find an issue with the motor it could be in the flight control board as one of the FETs are probably not working properly...In that case you would need to replace the board.
Check for debris on the shafts and gears..make sure everything spins freely.