[Bekhor]

Thanks to both Brian and whpalmer4 for your replies. It is especially nice to see someone at Omni monitoring these forums.

Brian - your workaround very nearly did the trick! It is sufficient for now. However, on grouping by Project, Context Mode still doesn't expose the full project hierarchy; action groups are not displayed until the group itself has a due date, and even then it appears as a separate item to the subitems (and beneath them at times!)

I believe that whpalmer4's opinion on the data-model is correct, and explains this discrepancy. Action groups seem to be orthogonal to their subitems, and inconsistently so. It is as if they were added at a late stage in the design of OF.