[HereWeGoAgain]

Likely the battery is dead. Worth remembering that what you're trying to do is charge up the 12v so the voltage is high enough to close the hv battery contacts, not push enough amps to turn a starting motor. If the 12v is dead, it'll pull down the voltage of whatever you're trying to charge up with and never really get there.

This is an important thing to remember. I haven't had this problem with the 4xe, but our second car is a full EV and we've stumbled across this problem. We have a plug in jump pack with two modes "start" and "smart charge". "Start" works by providing a surge of current to turn an ICE over. It won't work with our EV, the computer boot up process last too long before the HV can take over.

We ended leaving it on smart charge for the better part of an hour and then it had enough juice to boot; it is possible it needed less than that, but that is when we went back out to check.

 

[HereWeGoAgain]

This is really a crappy scenario.
All of this headache, heartbreak, Blood, Sweat and Tears along with the financial hit.
All of this for a dead battery.
What Jeep will do is replace the battery with the same crappy OEM battery and maybe you'll get lucky and it will work.
It seems unlikely that you are going to work on your vehicle, some people are mechanically inclined and others are not. There's nothing good or bad about either way however if you're not a mechanically inclined individual, my advice is find a mechanic who is good, honest and reliable. They are still out there, a honest mobile Mechanic. Then pay them to install a Odyssey AGM battery and be done with it.

I agree the most likely long term solution, to this issue, is to install a reputable battery.