VFD intermittently trips breaker on bypass relay

[Muzzer]

The MCB should never emit smoke or suffer a burnt out coil, no matter what load you present it. That suggests you either had a duff MCB or it was connected up incorrectly. Assuming this is a Type B (or Type C) breaker, you shouldn't need anything like a 20A or 32A rating just for a 2-3kW VFD.

If the inrush limiter / soft start relay is causing the problem upon closing, it suggests an intermittent fault in the VFD.

You mention an EMI filter. I wasn't aware these Huayang VFDs had any filtering. If you have fitted one yourself, that's A Good Thing but it shouldn't in any way cause the behaviour you are seeing.