Source codes can be created with various parameters that can then be chosen from a drop down menu when set up a marketing effort. When a drop down menu is created for "month" the drop down list displays the months alphabetically rather than in calendar order. Other drop downs have a similar "non-intuitive" displays.
In version 4.0 the underlying code was changed to 'orderby [MKTSOURCECODEPARTDEFINITIONVALUES].[DESCRIPTION]' which caused this change. There is nothing wrong, it just displays differently.