Scrollview stops after using LayoutTo on Parent

Hi there. The problem I'm facing is that I've a RelativeLayout composed by 4 StackLayouts, they're all side by side. Only two of them are shown at the same time. The two that are hidden have a scrollview, and when the user slides them to the front page they should be able to scroll, but they dont!

I can get them to work if when the app starts they're in the front page. If they are outside they won't work.

Sometimes I get this error:

unexpected nil window in _UIApplicationHandleEventFromQueueEvent, _windowServerHitTestWindow: 
<UIWindow: 0x7d882600; frame = (0 0; 1024 768); gestureRecognizers = <NSArray: 0x7d882b10>; 
layer = <UIWindowLayer: 0x7d8821c0>>

Any hints?

Thanks in advance!