I was in the process of making a command block to run a /setblock command using relative coordinates, when I copied some code from a different command block. I then pasted said command into a different command block. I expected the blocks to get placed where I had specified in the command, however, the blocks were not placed, and the output (within the command block GUI) said that my number was not valid.

So far I haven't been able to recreate the bug other than by copying the code from the screwy command block into a different command block.

In the picture, it says " '1' is not a valid number." There are two ones, but I worked it out that the z-coordinate value was the one it didn't like.