@Ondřej-Šutera If there is no data for these locations, then how come zooming in reveals weather data under these rectangles. And the rectangles are always in different places each time using the app.

When selecting "gfs" forecast model in the mobile app and viewing swell data, there will be gray rectangles across the map blocking some data. Upon zooming into the squares near a coast, they vanish, revealing the weather data underneath. However, they reappear when zooming back out. Graphic compatibility mode does not fix the issue.