Form QR code not loading on iphone

I have used the QR code to scan the forms document using the phone camera, then added the form to the iphone home screen so my team can access the form easily, without needing to sign into an account. This has been working for a year now but all of a sudden some phones aren't working. When I click the icon on the home screen, nothing loads at all. There is no error message or anything just a white screen. Any solution?