Reorder images in gallery not working

[Bluebit]

Hey all,

searched first, didnt find a topic with it or a solution.
Since some months I cant reorder images in my galleries anymore, worked perfectly before.
Basically now, when I go to "reorder images" it loads the view where you can pick & place images with your mouse.
But now once I pickup an image to move I cant drop it anymore. It basically sticks to my mouse arrow and keeps moving with it. I also cant pickup another image.

Any chance to fix it? I use Firefox, latest version all the time, didnt change anything else. Error started to occur form one week to the other.