Live Chess - Pieces Leaping Across Board

Can anyone explain how this happened?  Watch the video, on move 4 black moves a pawn to b4. But it mysteriosuly leaps across the board and lands on g5.

Caught it on camera this time... But in the game replay it doesn't show up.

And the b file is "blocked" for the rest of the game by the phantom piece on b4.

I've had this happen before, just caught it for the first time.

https://www.youtube.com/watch?v=aLlVrYnz0iM&list=UUC0Fa-t1cLLqTWVp9q2GT-A

That's pretty funny.  Nice job of documenting it.  First thing staff seems to ask is "how long since you did a cache clear in your browser?"  I know from personal experience that graphics get way strange if you don't clear it on a timely basis.  Is that what's going on here, or is it a bug?  Who knows, but I'd start with clearing my cache.

magic. /thread

I know how

You put it there on the analysis (you can move whatever you want) and then as a move. Then you just countinued the other moves

No, @themortar, you can see the game is live. Look at the clocks.

I just stopped moving and pulled out my camera, so you see the time still running off. Then I clicked the buttons to rewind to previous move to show the jump, then it goes back to playing live.

I hope it was fixed because it's quite ridiculous. You should have tried to move that "blank" b5-square forward, maybe the piece would appear again correctly.