Hi!
I have a problem on a Eachine X220s with FC Omnibus F4 V3 and IA6B receiver.
The receiver is configured with the IBUS protocol and i set the UART6 as a serial RX.

After about two minutes of normal use, the signal becomes intermittent.
This is the video of the problem: 
If i set the rotation of the engines through betaflight, they rotate without interruption.

I turned off routers and mobile phones thinking of any interference, but the situation remains the same.
I did a test even with the VTX disconnected.
What could be the problem? 

Thanks.

You are testing on the bench without props. PID is active and therefore trying to correct the quad. You will get sporadic motors movements. I would try a hoover test.