While I was playing on my realms, just out of the nowhere, the chunks around me started flashing and causing me to get headaches. I stopped playing for about an hour, and when I logged back on, they were still doing it. They weren't completely unloading, but rather becoming invisible. I have captured a video to show you. The link is here: https://www.youtube.com/watch?v=AnUDMHyT2KY&feature=youtu.be . If you have epileptic seizures, do not watch as the chunks flash rapidly. I am unable to play Minecraft as it gives me lots of headaches. This only happens on certain graphics cards, so if this doesn't happen to you, there is a screenshot of the graphics part of the debug menu in Minecraft. I searched for a lot of keywords relating to this and all I could find is MC-129, which was supposedly fixed in 14w31a, although I am in 1.8.1-pre3.