(Sugar Version 4.5.1; Contacts Module)

In Studio I set up some custom fields. One of them is a Multiple select called Category.

I have successfully added them to the Search forms, and can add more than one Category to a contact. However, when I add this field (or any other Multiple Select field) to the Contact List, using the Saved Search and Layout tab, they behave differently. Whereas all normal fields (text fields and dropdowns) appear with the two up-down arrows by the column name, allowing you to search in ascending and descending order, the fields which are based on Multiple Selects do not.

Is this a bug? Should I submit it as one? Is this by design?

I'm finding an increasing number of problems with Multiple select fields: this one, the one to do with merging fields and I'm also having the AND/OR search problem when using multiple selects. Are these due to some sort of limitation I'm not aware of?