Widget stuck at particular point when dragging to bottom

This is weird, but when I try to drag a widget to the bottom of sidebar it stuck in the middle, if I hold the dragging and drag it back to top it works but I can't drag it bellow that particular point.

Any help would be appreciated!

Edit

I recorded a video of what's going on, here it is: http://screencast-o-matic.com/watch/coh3YXf6sl Also, I didn't tell before, I am using Jetpack plugin for widgets visibility on certain pages etc.