left and right arrows

I'm new to Tygem, and I'm trying to watch the pro games.  I can see the current position (about 200 moves in), but I can't 'rewind' the game to an empty board, and then move forward (one move at a time) using the arrows underneath the board: they are greyed out.  The menu lets me see the kifu (numbers), but it's hard to read this way.

Am I missing a simple way to move back/forward through a game?
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