The "dynamic columns using ice:columns" posting on the icefaces.org forum
outlines the problem.

The table is rendering fine the first time, but on subsequent renderings, the
columns all have the same content. Upon testing, the submitter of the post
found that columnDataModel.getRowIndex() was returning 0 each time after the
first render.

I did some testing on my machine with an older version of ColumnsBean in the
Component Showcase. I found that not changing the columnDataModel recreated
the problem.

The problem is not evident in the current form of the Columns demo because the
content is the same in each column. However, using Rev. 11545 of ColumnsBean
will give you dynamic cell content in different columns. In this version of
ColumnsBean, the columnDataModel changes each time as the header String is
modified to reflect the new range of values in the column. When you make the
content of the columnDataModel static, (the same headers all the time) you
will see the first column repeated across all the columns.