Hello,
I'm just going to include my description of the problem and solution that worked for me. Feel free to reply with any other questions.
I believe the primary problem was that I connected the 2626 before updating the machine. Initially, it worked in a limited capacity before the major issues began.
I think the biggest problem was installing the 2626 firmware before properly updating the Dell TB16 and XPS 15 9550. I didn't realize I was lacking the bios update, controller firmware etc.. I think i made this mistake because my previous interface was working fine.
When the updates were completed out of order it created a problem. I reinstalled the 2626 firmware and it worked for a moment before i had another issue begin. I tried a few other things before installing the 2626 firmware which bluescreened the xps15.
Once I disconnected and reconnected everything according to the documentation things have improved and I believe I'm getting closer to expected performance.
Be sure to sync the sample rate with your daw!
Thanks for reading this and I'll let you know if something changes.
Have a good day
Nick