Hello there. Hope you can help. Family member had new gutters installed. They appear to be angled correctly. Using hose, Flooded roof with water and it went to downspout. Did not flow behind gutter. That’s good. However, at the other end, there is a low spot and the water traveled there. Considerable stream, circled location in photo. Asking installer to return and fix problem. It’s an almost flat roof, no tiles. Previous gutter didn’t leak this way. If this were your project what would you expect the solution to be? Thanks for your help.