It looks like they cut the top seal short........it should extend past the vertical seal and end at the edge of the channel. It looks like there is a pretty good gap in the vertical seal between the top end of it and the top one. It should be tight to the underside of the top seal. Water will run across that top seal until it gets to the end which since it appears short will drip off onto the end of the vertical seal or it will roll back the underside of the top seal into the gap. Then its in your door and on the canvas. You would be surprised at the amount of water that can go through a small gap.
Maybe take some more pictures of those corners tomorrow and take them from the front more so we can see how the seals fit together. Its hard to see on that one.
2017 Roo 23WS
2015 GMC Sierra 2500HD