upload new media item - always have to drag on twice

[helenvarley]

this is something that i've noticed for a long time: when i drag a file to upload a new media item, the first time it does not work. i have to do it a second time, and then it works. it's not an urgent problem as i think most people will try again if it doesn't work the first time, but there must be some bug in the system because it happens consistently, every time.

@vickis have you noticed this?