Printify is by far and away the absolute worst company i have ever dealt with that is not an outright scam. I have had multiple issues that have affected my sales stemming from a lack of structure within their company. Some of the reoccuring problems:
TL;DR- this company is too big for their pants. They are in no way equipped to handle any orders.
There is only one positive thing that I can say about the combination of Printify, your take on the "company", and my personal experience having to deal with Printify... And that is the fact that at least I know that I'm not the only person who has been scammed by them. Your review was literally spot-on. They were responsible for my Etsy shop being permanently shut down, due to 20+ orders never being fulfilled, which was the sole responsibility of Printify. The funny thing is, and by funny, I mean not funny at all is the fact that I paid Printify for all of the orders, then Printify just decided that they were just going to steal my money and not print or ship the items that were ordered. Then on top of that, I was responsible for issuing full refunds for the 20-30 orders that I had already paid Printify for, and those orders totalled over $500 that I had to pay out of my own pocket for. And the part that is absolutely inexcusable is the same thing that you experienced dealing with them... They wanted me to show proof to them! Completely ridiculous. I filed a complaint with the Better Business Bureau, and I still haven't received any of the money that they owe me regarding the situation. They also pay companies to leave positive and highly misleading reviews for their business. You can spot them all over the internet.