I really preferred not allowing support to have access to my computer, and they don't seem to be able to handle it any other way. (Twice someone was working on it, and twice the phone line was dropped.) So if anyone else has this problem, I did go into the MD Form 502SU and in the Income from US Obligations Smart Worksheet, I manually entered the capital gains on line B. The software correctly added this to my existing amount on line A and put it into line ab of the 502SU form. And there was a subsequent drop in MD tax after I went all the way back through the MD form - so adding the amount into the 502SU form did not trigger the recalculation of the tax on its own, but following through the interview again did.
