App not working properly – Checkout 51: Cash Back Savings Review

I do not want to rate this app poorly for its current malfunctions. I own Apple devices and since the addition of gas rebates my app has not worked at all. It opens normally but then goes to a black screen with a little white box in the left top corner of the view page. Basically, not useful to use the app. The screen does not expand or open properly, making this app useless, which is disappointing. I have closed the app, deleted the app, and reloaded the app nothing works to fix this problem.
Review by ANeighbor on Checkout 51: Cash Back Savings.