The Scale override button appears to be inactive.

[GRAFKOM]

Personally, I consider it a bug that the Scale override button in the Transform panel looks inactive even though it can actually be pressed.
Most users don't even try to press this very important button because it looks like it's inactive.
Please change the icon as I gave in my proposal and everything will be clear.

[GRAFKOM]

Transform panel

[GRAFKOM]

This icon is probably meant to represent proportional scaling.