I had the same issue booking the first part of a 2-4-1 over the weekend. Before the 2-4-1 was applied the charge for 2 x F GLA-LHR-DEN was 218,000, where it was 200,000 from LHR. As I was booking it online and knew I had to add on the return leg on later this week, I went ahead and booked it.

I tired calling the Gold Line, who passed me to the Avios Team, who then tried to pass to pass me back to Gold Line but cut me off. Meaning I had no resolution.

Rather than calling back I reached out to the Twitter team (who are normally great). At first I got the same reply as others. However when I pushed back asking when the policy changed etc, they then opened a case and are investigating it. They said they needed a few days to look into it.

Not it had an update yet but that was only on Tuesday.