In a 3D chart, when there are columns of various heights, it’s possible that some of the taller columns hide other shorter columns placed behind them. This is especially true with 3D charts that have a Z axis. One of the ways to make the columns placed behind visible is to make the taller columns transparent. The other way to solve this issue is to rotate the 3D chart a little so that you end up with a better view where the shorter columns become clearly visible.
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