Motor stall alarm on VFD panel and Overcurrent alarm on MV breaker

From my experience it is probably due to some mechanical problems eg, bearing, or damaged mechanical parts of mechanism driven by motor causing stall , which then sense by variable frequency drive and resulting over-current causing mv breaker to sound an over-current alarm.

Motor itself is stalling due to bearings possibly seizing or whatever the motor is driving is mechanically damaged. A quick test would be to isolate the power and remove the motor fan cover, then turn the fan by hand.....if it doesn't turn at all you know for sure its the motor or downstream equip. You would only be getting these problems because of overcurrent. Phase failure could also be a root cause ramping up the remaining phases into overcurrent.

Further to that, if you don't find anything at motor end, you can also check by isolating motor (from motor side, not from VFD side i.e. cables still connected to VFD) and start VFD. If is still trips, it can be either because of line to ground capacitive current spikes (due to longer cables carrying high PWM frequency) or it can be nuisance tripping due to the fault in variable speed drive. In case of longer cables, a suitable choke at the output of VFD would resolve the problem.