i started having this problem yesterday .. it seems to be only in spawn chunks when i tp far away from the area it returns back to normal .. it's only happening on a server side for me i took my world into single player and there's nothing wrong with it
it exactly started happening when i placed around few chests in one area .. if that helps by any means
yea thats right it's been there since 1.6 it's working correctly in 1.5.2
Mineplex