If you send a chunk package with the same position of a chunk package you have previously sent the new chunk does not always correctly override the old one. Often the highlighting of blocks can be seen for the blocks of the new chunk, but visually the old chunk is rendered.

In the screenshot included it can be seen that I am highlighting a seemingly invisible block (from the new chunk) yet the old chunk with air is rendering.

This bug is a major issue for servers as there is few ways to get around it (off-setting of the chunks means that the problem is only hidden, and ghosting issues can still occur).

It should be noted that breaking a block in a location where this visual error is present begins to render the new chunk, but still leads to other problems.

Devices Tested Upon: Google Nexus 5, Samsung Galaxy S7 Edge