How to set Scrollbar Thickness < 5.0f?

Every time I set my horizontal scroll box’s scrollbar to a thickness to less than the default of 5.0 it fails to do so.
The scroll bar shows that it is < 5.0 in the Designer Window, but when I playtest in “Selected Viewport” PIE, “New Editor Window” PIE, and “Standalone Game” it shows the default 5.0 thick scrollbar.

How can I set the scrollbar thickness to less than 5.0?

That is weird have you made sure you are saving the widget before you hit play

Sorry, been awhile since I checked AnswerHub.
Yes, I do a manual compile and save of everything before each PIE test.

Necro bump, I have the same problem and really want an answer, this is messing up my styling pretty badly. Also, the thumb graphic isn’t responding to image sizing either, it’s being forcibly distorted to the same proportions no matter what I tell it. And I am compiling and saving constantly as I test, that’s not it.

Anyone found a solution for this ? I have the exact same problem…