"I have partially solved my problem. If the ESC initially gets a signal, that is equal or slightly higher, than the PPM Min Throttle value set in BLHeli, it won't arm. In Ardupilot you have to set the THR_MIN_PWM slightly below the value, that you…"
"I have the same problem, but with FVT LittleBee 30A ESCs. I have enabled PWM input in BLHeliSuite, but it still doesn't work. Since these ESCs are made for BLHeli, I don't think they need modification."