GUI scale does not visually update when the option is changed using the keyboard and without the mouse

I tried to play Minecraft without the mouse, selecting everything with Tab and Enter, so I had set my GUI scale to 2 and I wanted to set it to Auto. I went to the Video Settings, I hit Tab enough times to reach the button and I clicked Enter to change it. Although the number DID change, the actual GUI scale DIDN'T change, so I continued to hit Enter but it still didn't change. I hit Tab until I reached the Done button to see if that would work, but it didn't. When I got back into the Video Settings, the number was still wrong.

How to reproduce:

1. Go to your Video Settings.
2. Hit Tab several times until you reach the GUI scale button.
3. Hit Enter to change the GUI scale.

What I expected to happen was:

Both the number and the actual GUI scale would change.

What actually happened was:

The number changed and the actual GUI scale remained unchanged.