Problem description: 
Sorting left to right (sorting columns) does not work correctly.

Steps to reproduce:
1. Open a new empty Calc document
2. Enter the following values to A1:C2

MyTitle   A    B
MyValue   2    1

3. Select the six cells in A1:C2
4. Click Data -> Sort
5. From options select "Left to right" and "Range contains row labels"
6. From sort criteria set Sort key 1 to MyValue, ascending
7. Click OK

Current behavior:
Nothing happens.

Expected behavior:
Content of columns B and C should be swapped since 1 < 2.

A slight variation of the problem occurs if I select the entire rows 1 and 2 for sorting with the same sort options as above. This leads to rows being incorrectly swapped.

This problem did not occur in 3.5.

Platform (if different from the browser): 
              
Browser: Mozilla/5.0 (Windows NT 6.0; rv:15.0) Gecko/20100101 Firefox/15.0