Scroll bar is not clickable in iCloud.

The scroll bar works in all other places.
But when I enter iCloud, the scroll bar doesn't work at all when I try to move it up or down by clicking the mouse, as indicated by the red box in the attached photo.
I have to move the scroll in the middle of the mouse to move the screen up and down.
But if I want to quickly go up and view all the files because there are a lot of files, I want to press the scroll in the red box with the mouse cursor to look at it.
But that doesn't work and it's very frustrating.
Does anyone know how to solve it?
The symptom is not only when using a laptop, but also when using it connected to a monitor.

I have a Blade 15" and it's a 4K touch screen.