Here's the test to determine if inverter is bonded. Set multimeter on ac volts. You should read 120V from hot to ground, or from hot to neutral. You get 0V from ground to neutral.
It is not bonded then you get 60V from ground to neutral, and 60V from ground to hot.
The 60V that you may see has nothing to do with any type of bonding. And, it's only 60V when measured with a high impedance meter (like a digital meter). If you measure it with an old analog meter, it will only read about 3Vac. The 60V is produced by two capacitors connected from hot to ground and the other from neutral to ground. They make a capacitance voltage divider. That's not their job in life, but just a byproduct of their real function (emi filtering).
