In the iOS mobile app, for expense reports, there are tabs for "Details," "Expenses," and "Receipts."

I used the Receipts tab to add images of receipts during my trip. After my trip, I imported credit card charges to the Expenses tab. I can't find a way to add the receipt images I already have in the "Receipt" tab to the expenses I added. When I click on "Add Receipt" in the expense, it gives me 4 options: Attach via Camera, Attach via Photo Album, Receipt Store, and Missing Receipt Declaration. None of these options allow me to select receipt images I have already added to the Receipts tab. Selecting Receipt Store gives me a message that says "You have no receipts."

What is the purpose of the receipts tab? How can I add those images to my expenses?