Best practices is to always use sidekick with cf# in URL.
I also tried this on my 6.2 instance, but i am not able to reproduce this.
Can you please check when Sidekick is coming blank, is there any errors on browser console or error in AEM error.log ?
ok, But on using sidekick with cf# in URL, i am not able to used side kick component. on dragging it give warning sign and also
an error in browser:-
Uncaught TypeError: Cannot read property 'getX' of null at CQ.wcm.Sidekick.DragZone4ContentFinder.CF_b4StartDrag (widgets.js:158663) at CQ.wcm.Sidekick.DragZone4ContentFinder.IDDM_startDrag (widgets.js:158809) at CQ.wcm.Sidekick.DragZone4ContentFinder.IDDM_handleMouseMove (widgets.js:158840) at HTMLDocument.h (widgets.js:11678)