The game has a feature where if you hold control and middle click on a block (The middle click is bound to 'F' in my condition, and the swap hands button is 'R'), it will save the NBT data. Obviously, this is useful while making command blocks, as it means that I can quickly copy blocks, and move them over a block or two if I need to.

However, sometimes, when I do this, the command block becomes "disabled". Everything is fine, except for the fact that it just no longer works. None of the following things work. Updating the block with normal blocks, or redstone blocks. Changing any of the settings including changing the block type, conditional/unconditional and need redstone/always active. The only way is by copying to the text, deleting the block, replacing it, and the pasting the text back.

Steps to Reproduce:
1. Ctrl + Pick block a command block with something in it. Probably a /say command in a repeating command block to make results easier to spot.
2. Place it
3. If you are lucky, the glitch will occur, though it quite rare.
4. Otherwise, you could watch the video attached as proof.