Reminds me of when I tested the three-light tester against various inverters.
It showed three lights with all my different model MSW inverters. It showed only the middle light (open ground) with a PSW inverter I had.
It does not show proper lights with my inverter gen floating neutral.
Also there is the business of the inverter gen not being the same as some built in gens which act more like they have MSW.
So, it might be that your gen is one of those non-inverter types that would show three lights, same as a MSW inverter?
