I must be clearly doing something wrong. Every time I change the batteries be it the house or chassis batteries I end up losing some sort of function. First time changed batteries I lost the ability to turn on and off the chassis battery inside the coach. This was maybe 2 years ago. Coach has pretty much sat in that time span and the chassis and house batteries needed to be replaced again. Now the generator wont start without the key in the on position and it will shut off when I turn the key off. I swear I'm putting everything back the way it was lol. Any help??

You clearly aren’t using it enough

This is true. Life interrupted my racing lately. Had to get that squared away. Now my toys are all jacked up

Well crap! Only the smart ads part of my reply showed.
The switches for the batteries are powered by...the batteries. I have found those solenoids get voltage sensitive as they age and if there is any terminal corrosion. So make sure you have a full charge in the batteries. The solenoids often have their power right from the batteries. Mine became so unreliable that I just left them on a nail I replaced them.
I suspect maybe your rig ties coach and chassis batteries together when the key is on. Maybe one set of batteries is low or dead?

All brand new batteries but anything is possible. I'll check tomorrow

I had the same thing happen a couple years ago, had to turn the key on and/or start the chassis engine in order to start gen. found out wiring was corroded enough coming from coach battery to reduce voltage/amps to gen. By turning on chassis engine it was like giving it a jump start. No corrosion on terminals, but a bunch in the wires. When I turn off chassis engine switch the gen would die, it was not getting any voltage to stay running, just like unhooking a battery cable.

That is exactly my scenario. I’ll look in to the wiring. Thanks