Can motor ground currents be generated by a 2-phase controlled soft start, similar to common mode voltage/current generated by a PWM vfd?

Never seen any common mode voltage problems caused by soft starters, but plenty from VFDs

Our customer has a system powered by a generator, running a few fairly large (50, 60, 75HP) motors. They are using 2-phase softstarts with bypass and are seeing 20-30% imbalance on phases during start, along with almost 6 amps ground current. Once the bypass kicks in, all problems go away.
I have also discovered some ground loop issues, which may be contributing to this problem.

From experience - yes if no bypass contractor is fitted on the soft starter - leads to bearing pitting, thinning grease and ultimate bearing failure - solution insulate one motor bearing housing - normally NDE or fiit insulated bearing - additional fiit one earthing brush to shaft