I have also experienced this issue as well. I didn't know it started happening until someone mentioned it. After some research myself, it looks like a potential issue with Safari, which works across all iOS devices, and Safari on the Mac. On the Mac, if I used Chrome, it works fine, so, it's possible Quickbooks made some changes in behavior on how the PDF loads in Safari, or Apple did. Unfortunately on iOS, using another browser doesn't solve the issue. 

Hopefully Quickbooks will resolve this soon.