In general, that is the case with most 3-phase inverters. It is common that they only use the neutral for the instrumentation purposes of measuring voltage and phase. NEC705.28(B)(2), formerly 705.95(B), allows an EGC-sized neutral if the manufacturer confirms that this is the case for that particular inverter. We're talking milliamps of current. A clamp-on ammeter calibrated to the current you expect on the ungrounded wires, is not even going to be sensitive enough to pick up the neutral current, when only used for instrumentation purposes.
The one exception I know about is the Fronius IG Plus units, that you can no longer get. This working principle could still apply to other inverters, I haven't ruled out that possibility completely. It also would apply if you are combining a triplexed group of single phase inverters operating phase-to-neutral, because their arrays won't necessarily perform uniformly. Fronius had a 11.4kW 208V version that applied its outputs across two phases each in a delta-manner, and a 12 kW 277V version that applied its outputs phase-to-neutral. The inverters were built with 3 internal power stages, each producing the phase-specific AC ouptut. There was a mix-mode where it would cycle through operating only 1 or 2 of the power stages at the same time to be consistent with the DC power available. So if you had 8 kW dc sourcing a 12 kW inverter, it would only operate 2 out of 3 of the power stages in order to improve efficiency. There was an alternative to mix-mode called balance-mode, which would uniformly operate all 3 power stages in the event that the utility requires balancing.
Because of this, the 12kW wye inverters in this family would require a full size neutral. In mix-mode, the inverter could potentially put the full load amperes on the neutral conductor. It would never put the full load amperes on all 4 conductors simultaneously, so it would be unrealistically conservative to treat the neutral as a CCC for derating purposes. Once all 3 phase wires are loaded, the outputs would be equal, and the neutral current would be zero. 12kW at 480V is small enough that you'd put it on a 20A circuit, so the individual inverter would require all 5 conductors to be uniformly sized at min #12Cu anyway. But where it would be significant, is for the aggregate output, after you combine 10 of these inverters in a 200A panel. It would make imply that the aggregate neutral would need to be #3/0 Cu instead of #6 Cu.