Missing Pixels On Windows 10

I created a world to make a find the button map on. When I went into the blocks to grab materials to build with, I realized a lot of blocks were missing pixels, which makes them look corrupted and odd. Please fix this glitch. I don't know how or why this happened, but I don't like it. Also, if you don't see the bug, look at my inventory of the blocks I'm holding in this screenshot.