Autolayout input bug?

Only this week,
I noticed AutoLayout (spacing input) behaving differently.

I don’t seem to be able to delete the value to automatically transform into AUTO anymore.

For example, if I delete the value of the spacing of 16 pixels in an AutoLayout frame, it turns into Auto.

but now, if you backspace (delete) the value, and click outside the input, it retains the same value.

It used to behave the same way it would if you deleted (backspaced) a line height property and it turned into auto. Now it is not.

Has anyone else experienced this?