Problem with channel 2 on PWM

Hello. I’m new here and I don’t know English well. I would like to get help with PWM. On channel 2, which is configured for the drone motor, it does not send a signal. When power is turned on, a beep sounds every second. During the test of all motors, only 3 out of 4 work. Thanks in advance for your help.

Hi Marcin, so which PX4 version is this and what hardware?