Context menu on dynamically added image - what was right-clicked on?

I've a context menu (IMAGE_MENU) with two menu actions. I'm dynamically adding images to my view:

data(image) = cl_wd_image=>new_image(

    id = 'UNIQUE_ID'

    source = '~Icon/Cancel'

    context_menu_id = 'IMAGE_MENU'

    context_menu_behaviour = cl_wd_image=>e_context_menu_behaviour-provide ).

data(flow_data) = cl_wd_flow_data=>new_flow_data( element = image ).

i_container->add_child( image ).

All works fine. When I right click on the image, I see my context menu. The problem is that when I chose a menu option, the action triggers, but WDEVENT doesn't tell me the context element.

WDEVENT->PARAMETERS has the value of the selected menu option, but CONTEXT_ELEMENT points to null.

WDEVENT->SOURCE_COMPONENT_ID (which is what I expected to have the value of my image_info-name) is blank.

Any ideas?