Microwave not working.

We just switched trucks and this one has a Xantrex pro XM 1800 inverter. Our microwave is acting funny and not heating the food. It worked fine in the last truck. The microwave is rated for 1200 W. This inverter is rated for 1800 W with 3600 W possible at peak usage. It should have no problem at all running this microwave. I was thinking it might be the wiring in the truck so I hooked up an extension cord directly from the inverter outlet to the microwave and I still have the same problem. I went on the website and no answers there. What do you think? I have no electrical instruments to measure the output. It has a readout in the truck measuring input voltage and output current in Amps and output power in kilowatts. the input voltage reads 14.0, input current reads zero and output kw reads zero with nothing plugged in. When we turn on the microwave the input current reads 003 and output power reads 0.03. None of this makes any sense and doesn't seem to be enough to even get the microwave to light up let alone pretend that it's working. The microwave does turn on but does not heat the food and the carousel likes to change direction and it never did that before.

 

The inverter or the microwave? The side of the inverter has a GFI 115 V receptacle on it. The light on the receptacle is green. My wife connected a string of Christmas tree lights to the outlet and those work. I am baffled here

 

I am thinking about testing it by plugging in my wife's curling iron. It says it only uses 115 W so that shouldn't be much of a problem. Is it possible that if this inverter is bad it will fry that appliance too?

 

Tried it both ways and no difference. We got the truck back to the terminal and took the microwave into the drivers lounge and it worked fine in there so it has to be the inverter. I can't figure out how the inverter can run the Christmas tree lights but not the microwave.