I have never ever been disconnected from live chess, so I do not know what it is like. but it's probably because it cannot get a connection so it dosen't know where the pieces are.
Pieces are hidden while Reconnecting?

Regardless, the last known position of the board was displayed and should continue to be displayed until the updated position is received, no excuses. After all the clock is ticking down and every second counts. I have lost won games because of this.
The first time this happened I said forget about it, The last time I only had a couple of minutes left. Two minutes spent watching a blank board during my move. I was ahead in material, during the end game, and had a good chance of mating. By the time I finally saw the position I had less than one minute left on the clock. I lost the game because of time. I went from 2 mins to a dozen seconds on one move (a move that I was denied the ability to plan). This is ridiculous.
You both say that it is because of the server... NO its the CLIENT side software thats at fault. Instead of displaying a blank board the client should show the last know position of the pieces.
Why does the software hide the pieces when it's displaying the reconnecting message? This is annoying as my clock is still ticking, yet I'm being denied the ability to plan my next move. It would be nice to see the last know position even if it is one move behind your opponents current position. Either that or stop the clock during reconnection (which I am not in favour of to be honest).