giant chunks missing from world

Since the 1.12 update we just have a lot of bugs. Whole chunks are missing from our realm. Its not just like areas that aren't loading. They are gone. You can fly all the way down below bedrock into nothingness. It shows up black on the map too. I am attaching screen shots. Its pretty much unplayable in this area. I have video, but there is no way I could limit it to 10mb and have you guys see how devastating this is.