I'm assuming the Datasource load isn't happening because the DROPDOWN_REPORT dropdown box isn't getting updated. It's possible that the Datasource load is happening, however, and it is only the setItems method that is failing.
I did change the getSelectedText to getSelectedValue. In and of itself, that doen't change the behavior I'm seeing, but I'm glad to have it correct anyway.
I'm curious, though, if I condition the DS to only load if it isn't already initialized, how does that affect the setVariableExt method and the getMembersList that follow? Will the DS just be requeried, without having to actually reload it? If so, does that mean that Datasource loading and querying are separate actions in Design Studio?
Edit:
Apparently only loading the DS once doesn't affect the querying with a new parameter value. That's good to know.
I made the changes you suggested, and I still see the behavior. It doesn't happen every time I change the Dropdown value. Most of the time it doesn't. But once in a while, I select a new value and the DROPDOWN_REPORT doesn't update. Also, when the update does occur, the application greys out for a second while the update occurs. This doesn't happen during the failure either.