Scanning 11x17 does not work on app

I want to use this app to scan 11x17 documents to my phone but it only seems to do 8.5x11 on the Epson WF-7620. I can do 11x17 scans on my computer but not this iPhone app. Please fix this issue as there is no setting to change to 11x17 scanning.

Jon S 1234 about Epson iPrint, v5.0.3