When you link a command block with "/clear" command in it to a very fast clock, you experience multiple bugs. First, you experience a chest lag. A chest lag is in which you try to place items around the chest with your cursor. However, the chest does not update itself.

How to replicate---
1. Open a server. The bug is very obvious in a server. However, this does not mean the bug is not present in singleplayer.

2. Place some dirt in a chest. Go into survival mode.

3. Link a fast clock to a command block with "/clear @a 46" command.

4. Keep the clock on at all times.

5. Shuffle the items in the chest around. The bugs will become very obvious.