If you have only played a club for shots within 50 yards of the pin then it won't show on the clubs page. These are considered short game shots and are excluded from club distance calculations. This means chip shots with an 8 iron are not included etc.
Shots marked as a positional shot are also excluded from club distance calculations, this means that a chip out side ways from the trees isn't included.
If you have simply not hit a shot with the club it will also not appear on the list.