EDIT
OK, weird. I just saw a new block get accepted and received the notification that I had received 64 GLX. This updated the 'Unconfirmed' entry in my wallet with the 64 GLX, but then this went back to zero in 2 secs. Balance not updated.
That sounds like an orphan, where someone else has found a block at almost exactly the same time as you did. Only one miner can win.
If you do 'listtransactions' in the debug console you should be able to see the orphaned blocks.