FYI - if you were my neighbor I'm sure you could identify even more of my personal and personality flaws. So I fail internet class. And I worry................................shoot me.
It appears from the outside looking in that your boost controller is not working as designed. I doubt your turbo, wastegate or wastegate location are the issue from looking back through a 100 pages or so to find pics.
Now that I've skimmed the manual on DC and Boost cut and watched a video (I put in the 20 minutes of work haha), I assume you weren't aiming for 18 psi. What were the DC and boost cut set to when it went to 18 psi? It took 1.5 seconds to go from a comfortable range to 18. According to a fellow on the video you can log duty cycle, but you didn't include that on your screenshot above.