I found a wrecked one and repaired it, then drove it home and have used in in combat all without issues. I've not tried starting a game with a vehicle as part of a scenario; if that does not work then 1) it's probably a Vehicles Expanded framework issue and 2) try starting the game then using dev mode to spawn a paladin, see if that works.

I don't know how to use Dev mode.
I have since just spawned with the parts to build it, and it seams to be fine... pretty sure its the same thing as when you try to add more than 1 custom structure to start, ( the fact that only one vehicle showed up, not the crash) I think you can only have 1 of each custom asset to start with.

I've had the same problem. I built my paladin from a wreak in one of the older updates. Since 1.5 however, my paladin won't load in even though I have 2 pawns stuck in there.

Yikes, thats very unfortunate, I didnt lose anything but the first 10 mins of a new game, but losing pawns after awhile is detrimental. Do the pawns show up on your Colony list, if so, maybe just create a caravan, and add them to it that is leaving the town, and then bring them back in immediately

On my last save there was a caravan (the paladin) already outside of the colony, I merged it to retrieve it, then the second it arrives it doesnt load in. The pawns still show up on the bar at the top and in the driver/gunner seats but I can't access the cargo. It will still pop up but it's completely blank. I don't know what else I can try...Really weird

Unfortunate. Strange indeed.... such is the issue with mods it seams.

I have a problem when forming a vehicle cavaran and the paladin aswell as many other vechiles don’t show up? Am I suppose to research or do something? Not sure what I’m missing

You need to research the different tiers of vehicles in order to build them, with one exception as far as I know if you find a Wreck of any tier on your map you can just restore it, without the tier research. Also I have noticed sometimes, that vehicles don't show up as options when forming caravans, especially some of the Wheeled ones, you need to have a Road or clear terrain around your Colony hex.

This is the issue I had. I found it an restored it but dosnt show up as a vehicle caravan. So annoying so we have to go by foot everywhere, even tho we have a vehicle

Or start near/ on a Road Hex, but the road actually has to intersect the Hex you occupy. It doesn't work if its adjacent, or you can try just using tracked vehicles.