I solved it about an hour ago! LOL!
So I've been struggling with these 4 frets for 2 weeks now. I read up on fret leveling. Did it using sandpaper (400 grit). It took a couple times. Then today my crowning file came in from Stew Mac and I did a pretty damn good job if I say so myself and that didn't clear it up... I was getting really frustrated.
Finally, I decided let me release the truss rod as far as I can go (dual action truss rod) so it went all the way and still no relief. Then remembered my conversation with Musikraft about the neck and they explained how that truss rod worked a little bit. I decided let me turn it counter-clockwise some more even though it was tight. I didn't force it, just turned it a bit more. Put the neck back on and it played clean... The action was preposterously high but it played clean. I figured what the heck, let's slowly and gently tighten the truss rod the other way and get the action to come down. Over the course of an hour or so, I tightend the truss rod until the action was where I wanted it. Low and behold the buzz was gone. I guess the neck went a bit cock-eyed or something and twisting the truss rod the other way corrected the issue because now the action is quite low and it plays clean as a whistle!
I'm so glad I stuck to it and didn't resort to a tech. I learned some cool stuff... Fret leveling, truss rod adjustments. Awesome! Can't wait to make another guitar...