for Loop stop with when previewing render progress

Question

I have been attempting to create a simple add-on to assist non-3D colleagues.

Part of the plugin uses markers as filename during the render sequence.

Below is the code that I use to render and save the image.

bpy.ops.render.render('INVOKE_DEFAULT', write_still=True)

But 'INVOKE_DEFAULT' stops the for loop. If I remove the code I don't get to see the render progress.

Is there a solution to view the render progress and save the images?

Here is the section of the code I use render and save the images with the marker names.

def execute(self, context):
    # get the scene
    scn = bpy.context.scene

    # get the output path
    output_path = scn.render.filepath

    # iterate through markers and render
    for k, m in scn.timeline_markers.items():  
        frame = m.frame
        marker_name = m.name
        scn.frame_set(frame)
        scn.render.filepath = os.path.join(output_path, marker_name + "." + scn.render.image_settings.file_format)
        bpy.ops.render.render(write_still=True)

    #reset the output path
    scn.render.filepath = output_path

    return {'FINISHED'}