Cloning chests with contents inside of them onto chests with different contents (both of which are facing the same direction) outputs "No blocks cloned" even though the source chest had overwritten the one at the destination. For example, if I clone a chest entirely full of cobblestone onto an empty chest, the chest full of cobblestone will be cloned to the destination, so the clone command was executed successfully, but the game still outputs "No blocks cloned." Because "No blocks cloned" is what a command block with an applicable /clone command would output, a conditional command block next in a chain would not execute its command.

This issue is hard to show with a single screenshot, but I have sent multiple of them, labeled via their files names, to try to help show/understand the issue.