Slime Blocks Render Incorrectly

When you place down slime blocks, they render incorrectly, and go black in the middle, the more you place down next to eachother, the darker it goes, as shown in this screenshot:

To recreate this glitch, simply place slimeblocks down, next to each other, As big or as small as you want.

Note: Even though the picture is taken with a resource pack used, the same issue occurs without a resource pack.