Scrollable panel does not work after disable and enable action

I have made a simple list of objects using a UI Panel containing a Scroll Rect object. The panel works fine, it just scrolls as I wish and looks really good. But if I disable the panel and then I enable it again, it doesn't scroll anymore. Obviusly I disable just the parent object without changing anything else and, in fact, no parameter is changed during the disabling/enabling action. Any idea about this strange behavior?

Thanks in advance!

P.S. no code is involved in this action except the enable/disable script, which is banal.