Time for an update and good news!
I reinstalled the factory barrel in early January, took it to my local shop and had them test fire it in their gunsmith area. I had them put a 20rd mag through it just to be sure and it worked just fine. After that I emailed ILWT detailing the issues I had with the barrel. I had a call from Rob within the hour and we discussed what was happening and possible causes. One of his first questions was if the barrel had the extractor cut. He emailed a return label and I sent it back a week or so later. I did make a range trip after that and put 100-150 rounds through the OEM barrel so I knew for sure it had to do with the ILWT barrel.
Late February I received a replacement barrel with a noticeably larger extractor cut than the first barrel had. I didn't take a picture but it's much closer to the OEM barrel than the first barrel. I installed the barrel this morning and headed to the range for what turned out to be 120 perfect rounds. Maybe it's a tolerance stack issue, but mine won't run right if the extractor cut isn't close to factory.
Gratuitous dirty pics:
