After upgrading to DT 2.0.0, column sizing together seems to be broken when using the rowGroup option. See the screenshow below (note I have set "border-spacing" here so it is possible to see the colspans).
The leftmost column is expanding more than needed, which leads to a line break in the rightmost column.
When removing the "rowGroup" option (or downgrading) the sizing works just fine and every row fits in a single line.
