A TScrollBox will never work properly if you set its Align to alClient.
If you resize its containing form, you set up conflicting changes affecting the size of the scrollbox itself, and the positioning of its contained controls.
The idea of a scrollbox is that it knows how big it is, and if its contained controls are resized relative to that known size, it can provide internal scrollbars for the user to reposition the resized control.
But if the scrollbox does not know how big it is... how can it determine if scrollbars are needed or not?