Looking further into the OP, since this is a 1hp VFD with 400ft leads to the motor, the most likely reason that the drive is faulting on OL is due to the high frequency coupling of the output pulses into ground.
Whatever current that couples into the ground originates in the drive and causes the drive to read that current as if it was flowing to the motor. This makes the OL calculation in the drive wrong and causes faulting when the motor is not actually overloaded. I have seen this demonstrated by disconnecting the motor at the motor junction box and then reading output current on the drive. At 400ft of motor lead length, I would expect to see somewhere around .6amps flowing out of the drive. It must be going to ground since the motor isn't connected.
If this leakage current is well balanced, the drive may not fault on ground fault. If it's imbalanced, the ground fault may occur faster than the OL fault.
The reactor or, in even worse conditions, a dv/dt filter is exactly the right solution to this problem.