The generator is a big one - 17,500 watts. Still not enough do you think? Heat pump is two tons.
It’s not the watt output that matters, it’s how many amps. It it’s a 30 amp output and your heat pump has a starting amp draw of 45 amps it will never start the heat pump.
I could be wrong but I’d be willing to bet that’s your issue.
Get a room air unit and have that for a backup. Thats what we did.