See the attached image. The comparator clock is working, but only the command block on the left is getting triggered. (/say hi)

Steps to duplicate: Build the same structure you see here. Make sure there is only 1 redstone dust between the clock and the (faulty) command block.

I have noticed that command blocks must be 2 or more blocks away from the clock for them to work.

Oh, and there is an error message that says "unknown command..." in the command block on the right but the console command in the block is "/say hi"

Also... I believe this bug has been in the game ever since comparators were introduced... but I didn't want to type every version above.