Hm, that's encouraging. I'm sending another SM, this time with screenshots of the offer and posted activity. Will report how it goes.

BTW just out of curiosity, when selecting an Inquiry Type in the SM composer, what did you select for this? In my earlier SM I picked "Rewards Inquiry", but in this second attempt, I'm selecting "Others". I doubt it matters too much, but just in case (I am tired of the redirect loops that Chase Card Services and Chase Travel keep sending me on)