In live it can be a bit difficult to be sure you are claiming the draw at the right time, so I keep mashing the button after each move until something happens.
If you mentioned where exactly this repetition occurred it would be a lot easier to help.
3 Move Repetition Not Counted?
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The position after move 24 by white was repeated 3 times.
Move 30...Rad8 (moves 23 and 25)
Move 32...Rab8 (moves 24 and 27)
Move 33...Ra8 (moves 29 and 31)
Move 34...Rac8 (moves 26 and 28)
Are all threefold repetitions, but it's pretty confusing when they happen exactly. Maybe you were off by a move? Maybe if you wait 1 move afterwards you can't claim it anymore? I don't know. Should have been a draw if you claimed it on any of these.
Hence my suggestion that you should spam the draw button just to be sure. The computer doesn't mind, and if it's a human player they should realize its a draw anyway and it serves them right if they decline.
In the following game, the position was repeated 3 times and I offered a draw, thinking this was the way to claim the draw. However, the computer (my opponent) was able to decline my draw and the game was continued. I am asking that have you ever had this problem before and is this normal on chess.com.
Link to game: http://www.chess.com/livechess/game?id=441927098