The command block keeps saying that "You cant place blocks out of the world" when I use the fill command

Well when I use the command block to use the fill command it says "You cant place blocks out of the world, I was playing on Minecraft with my friends I needed to use the fill command to make the super flat for just a small part you know like for parkor maps anywhys when my friends where building I found out that its not working? I dont know if this is a bug but it did this: