Game Center Turn based issue with the handleTurnEventForMatch in sandbox mode

I am building a turn based game using the Prime31 plugins for GameCenter and GameCenter turn based. I have deployed the game to two devices (iPad en Iphone 5S both using latest version of IOS7)

After starting a new game and ending the turn by calling EndTurnWithNextParticipant(playerId,matchData) the other player does not always receive a handleTurnEventForMatch which leads to a situation where both players are waiting for their turn. If I check the game status through Game Center app for the current player it shows 'It is THEIR turn'. When I refresh the Game Center app by closing it and starting it again it shows 'It is YOUR turn'.

My first thought is that I have not correctly wired up things in my game but when I tried the same thing by using a clean project and the example scene from Prime31 which is provided as part of the package, the same thing is happening. Sometimes ending a turn works and the other player receives a notification and sometimes (most cases) it doesn't. Even with this example scene.

Is this something related to Game Center sandbox servers?

Any help much appreciated!