This sounds like an issue with the carrier. Saying it "disappeared" before reaching the local PO box is a bit vague. I think you should reach out to the shipping service if Dean isn't getting back to you.
From what I understand, they are a "mom and pop" shop so they might just not be super tech savvy. This is even mentioned in the reddit thread I assume you're talking about.
Personally I've only seen good things from them. Ordered a 3 inch belt that got to me in less than a month and my GF ordered one that got to her in about 2.