I'm not sure if something changed because enough people brought this issue up, or if I just got lucky with the right online chat agent, but I raised this issue today and they were able to do something on the back end to get it resolved and I successfully filed my W2s. I referenced the response in this thread from the Quickbooks team (pasted below for reference) and I'm not sure if they were able to look at the ticket number and see a solution or what. I hope everyone who is struggling with this can get it resolved - I have no idea what changed this year! 

In the online help forum, I saw this post from a Quickbooks admin, so it seems to be a known issue: "Currently, when filing a W-2s form a pop-up appears stating a message shows up with an action the customer needs to take and a link to click"When clicked, the link takes them to a page with the error "We're sorry, we can't find the page you requested". I recommend contacting our live support to add your account to the affected users list. Just provide your updated email address, and the investigation number, INV-97858, to be notified through email. "