Hitbox is not working?

I have minecraft on the PC, I press F3+ B it is Hitboxes: visible but you can't see. I've tried 1.14.3 & 1.14 both are not.

I've tried it and it works for me. Just try it again. If that does not work, try reinstalling the Minecraft version or Minecraft. How do you reinstall a Minecraft version, I explain to you now:

Press Windows key + R
Enter there to "% appdata%".
Open the folder ".minecraft"
Open the folder "versions".
Delete the 1.13 or 1.14.
Start Minecraft
If you now select the 1.14 or 1.13 should download this again.

That should work first. If that does not work I have no ideas now.