Whenever I capture the gold on Moria Gold, the entire world becomes transparent. It looks like it just isn't rendered, but the blocks are indeed there, just invisible.
This problem has never happened to me, but it has happened to my brothers who play on the server as well. The only way I'm aware of to fix this is kill yourself then respawn.
If you press f3+a it reload all your chunks, but it also have side effects such as: stoping your movement for a short time and sometimes pushing you 1 block (don't use this in mid-battle)