[TJ Clark]

This is just a guess since I’m not very familiar with Outback inverters.  It sounds as if the problem is frequency related, works fine on shore where it sees 60hz.  It also seems to work with an AC unit on with generator running but when the AC is off it shuts down.  When the generator is unloaded the frequency is around 63hz but with an AC unit on the frequency drops to a level acceptable for the inverter.  

Does this sound like what is happening?

Yes. The logic is sound. 

Let me add one thing I see now should have been in the original post. 

This started recently. I have been full time in the coach for a year and this started in early June. 

It took awhile for me figure out that it was happening and when. 



If it is the frequency what changed?

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Its hard to say, if your batteries are fully charged and in good shape then the inverter doesn't really care if it has AC voltage or not. But it is strange it only does it with generator so I would check the automatic transfer switch first, could be some contacts need some sanding or filing which is creating a low voltage which the inverter see's and shuts down.

Is this akin the points in the distributors of my youth? 

Pull the cover off the ATS and it becomes obvious?