piece not dropping.

This has happened 3 times today. Once was in this game:

on the final move I picked up a piece to move it, and it wouldn't drop when I clicked. So I couldn't move.
I had to resign because I couldn't complete the move.

Today is first time this has happened.

To help debug, please tell us your browser version. Also, what device and device model are you playing on? Are you using a mouse or a touch screen? Are you moving by drag or by clicking two squares?

it happened to me too, i play on a laptop with touchpad

Issue fixed, we believe.