Random blocks disappearing.

Random blocks disappear when loading back into the world (single player survival). They are completely gone, not just invisible or not loaded in yet. Closing and restarting the game doesn't help. Only way to fix this is to replace the blocks that disappeared. It didn't happen the first time opening the world after the hotfix but like on the 6th time opening the world after the hotfix. I Wasn't able to recreate the bug.