Player goes invisible and falls into void.

I was playing Survival Games on the FyreUK server and soon enough I found out that:

• I couldn't open a chest
• My team mate couldn't see me
• Nobody could see what I was writing in the chat
• When I was walking it seemed like I was walking on ice
• The rain turned black
• Whenever I dropped an item it vanished out of my inventory but there was never an entity to show up
• I found that the chunk around me is pitch black as if there was no chunk
• The chunks more in the distance were loaded
• The chunk I was in was clearly loaded as my team mate was in the same chunk
• It was like I was inside the ground but could see outside of my chunk boundaries