First why not post what make - model of inverter/charger you have.
If you tell me you don't know, then please start looking for it.
Some people like to know the make and model of the Rv you have also.
Example, my MH has a Xantrex Inverter AND charger combination unit. I also have a inline fuse to the inverter/charger batteries.
I need to plug in or run the generator for it to operate.
It can run on generator but not work on shore power due to a bad automatic transfer switch (ATS).
Now I can go on. but please think about this, for me, I need additional information to help. Others may chime in, but I do believe we all need additional info.
And finally, are you a DIY'er, able to use a voltmeter and limited tools? If not, then you really need to call someone who can, to help you.