I am not absolutely positive about the limits of what EA will do here, but here's what (I think) I know.
[Note: I'd love to be corrected if I am off base. If anyone has better insight on any of the following, please chime in.]
Compartments - at least customized ones - are shown only for element types that are specifically defined in UML as having these display options. In most cases this is restricted to various 'rectangular' element types, such as Class and Object. EA is pretty good at allowing you to show compartments in these cases.
There are other cases which are specifically defined, such as state elements. Once again EA handles this fairly well, though you are generally restricted to those compartments specifically mentioned as display options in the UML specification. That's why you can only display a limited number of things on a state element.
In order to display compartments for other element types, you pretty much have to force them into the rectangular form, then display what you need. Depending on what you want to achieve this might be satisfactory.
For use cases and actors this can be done by right-clicking the element and choosing Advanced | Use Rectangle Notation from the context menu. You can switch back - losing any compartments - by once again right-clicking. This time the option will be found as Advanced | Use Circle Notation. [For use cases, actors will read slightly differently.]
Here's the catch: EA only supports rectangle notation for specific element types. AFAIK this is restricted to use cases and actors. This also appears to be the case in EA 7.5 (beta 1), at least as far as the help file (also in beta) says.
So...
Try the above on an activity element. If it works you might have a satisfactory result. If not, try it with the EA 7.5 beta (or production version when the time comes). Once again you might have a solution, though you'd have to wait for the upgrade.
If the above do not work, you can submit a feature request to Sparx requesting that rectangle notation be extended to activities (and perhaps other element types). Use the Feature Request link below the Support link near the bottom of any forum page.
David
