I think it has to do with your connection. I had a similar problem where my first move "did not reach the server". The move showed, but I had to go again and when a move that involved the original first move then it would disappear.
Bug observed when playing Computer-HARD
Perhaps. If so it was a curious co-incidence that it was when I was playing the computer (rather than people, as usual, when it has never happened to my recollection in more than 6000 games).
It took me 22 seconds to play that second move. I think by then I would be visibly disconnected.
Not sure if it was due to the program, but it would be quite a co-incidence if it occurred on the very rare (once in several years) that I have played this computer at live chess.
The bug was that several times in the first few moves, the interface took my move back! Very odd. I played 1. e4 e5 2. Nf3, but the knight would move back and it was still my move! I had to play the bishop's opening (2. Bc4) just to get the game started as it repeatedly wouldn't accept 2. Nf3
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Conditions
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Pick up Computer3-HARD's 3-2 challenge on Live Chess. Play a few games and then try to play another.
I was using Chrome on a Windows 10 PC