Magnum MM "High Volt AC" When Generator Starts

Customer recently had a failed Generac ~14 kw replaced with a new Kohler 14 kw.  Everything worked normally at the time.

A few days later when remote starting the generator the ME-ARC said high volt AC error.  Customer figured out if they left the generator run, but just opened the generator disconnect, then it would reconnect just fine.

Also stated their backup generator, a 1960s Kohler, will sometimes trigger the error.

The backup was measured by us to be running about 126 volts 62 Hz unloaded and the new main running 120.000 volts 60.00 Hz.  The old Generac was a 58 Hz model running unknown voltage because it is dead.

The Magnum MM manual doesn't really say much but the ME-ARC manual seems to indicate that high volts AC is only supposed to trigger around 150 volts so I suspect the inverter is over-sensitive to some initial voltage overshoot but it seems far fetched that the generator would overshoot that far when starting.  It does not rev up or do anything stupid when starting.

Thoughts/experiences?  Going to drop the genset voltage to ~225 or less and see if that helps anything when we get back out there.