dx, dy, dz parameters are not working properly.

The dx, dz, and dz parameters are not functioning as they should. For example: 

/testfor @[dx=0,dy=0,dz=0] shouldn't detect any players  yet it detects people as if it is [dx=1,dy=1,dz=1]. Basically, if you want a specific block (a 1-by-1 radius for example), the command block wil always form a 2-by-2 cube. To be specific, the area goes one block further than intended. This is extremely frustrating as I use this command in my adventure world for practically everything. I have a video demonstrating the bug. (This bug is also reported in MCPE-171423)

Thanks!