Are we certain/confirmed that it must be a round trip in order to receive the statement credit? I cannot find that requirement anywhere at all in the terms and conditions for that specific benefit.

Here is the specific bullet from Chase.com that describes the "Reward Flight Statement Credit" and paragraph d reads:

"d. The booking must be for a transatlantic international travel itinerary redeemed from Cardmember's Executive Club account with the transatlantic portion departing from the United States solely on aircraft operated by British Airways. The booking may include a connecting flight on a code share partner for the non-transatlantic portion of the itinerary."

I don't see any language that requires a round trip in order to qualify for the statement credit. There are additional bullets but the one above is the only one that relates to itinerary requirements but the full requirements can be found here:
https://creditcards.chase.com/travel...ways?CELL=6TKV (click "Offer Details" then scroll down to "Reward Flight Statement Credit" section)

Has anyone had success getting the statement credits for a one way flight, on BA metal, originating in the US?

Regards