command blocks can't recognize entities with "space" in name

If you place repeat command block and write command (name of the item with space) it won't work. But if you write command and pick an item without space in the name, it'll work. Why?

Link to video footage where I showed everything in detail: https://youtu.be/lQNBvJ2347s

Step by step to do this bug:

1. Set repeat command block, then do it always active and write a command /testfor @e[type=item,name=(name of item with space)

2. Set a comporator close to the command block and throw an item that you wrote in a command block

3. It won't work :|