Turned off iCloud Photo Library, some photos won't go away, others blank

I'm using iCloud Photo Library on my Mac and my iOS devices. I turned it off on my iPad to gain some space. All three iCloud photo features (library, stream and sharing) are turned off. The Photos app still shows a bunch of random photos, though. It also shows lots of completely blank photos. How do I get the iPad to remove these "phantom" photos?

The the following screenshot shows what the blank photos look like. There are also lots of random photos sprinkled in through the library but for privacy reasons I didn't include a screenshot of those.