Using Ctrl + Middle mouse wheel on a Chain, Repeating, or Impulse command block set to conditional mode will not save the mode. When you place the same command block down, the mode resets to unconditional.

Steps to reproduce:
1. Set a command block to conditional mode.
2. Pick-block the command block. There should be a command block in your inventory with a purplish +NBT text.
3. Place the pick-blocked command block down again. It should show by the texture on the block that is in unconditional mode.
4. Open the GUI of the command block and find that it is indeed in unconditional mode.