unreal engine using all of my cpu and none of my gpu

I’d say that’s a good thing, you paid for the entire PC, use the entire PC! Do stay vigilant of course, in the olden days there were dozens of threads like this:

Never experienced it myself, but too many folks reported the launcher using 70%+ CPU time consistently for it to be just a fluke. That should not be happening and is no longer a thing (that anyone talks about, at least).