I recently had a problem some straight table charts in a model that would allow sorting in only one direction. In other words, double clicking the header would sort by that header, but double clicking again would not reverse the sort direction. In fact, only the direction set in the Sort tab of the chart properties would work.
The chart had normal dimensions and expressions and no apparent reason for this behaviour.
The problem turned out to be that the first expression had been disabled. When I deleted this expression, sorting returned to the normal behaviour.
The lesson I learned here was that if I want to disable an expression during model development, demote it so that it is the last rather than the first expression in the chart.
Using QV 10 SR2