I just booked an itinerary that has an ATL-LHR leg in Business (I) for March 2024 and confirmed on both the AA and BA website that there is award space available in First. I called in to apply my SWU and the first agent was not able to help, so I HUCA and the second agent couldn't help either (though she seemed much more competent), so she went to the support team before coming back to me saying they couldn't apply an SWU unless I had booked into a higher fare class such as D, R, C, or J. Is that true? If not, I guess I need to HUCA, but what should I ask the agent to do specifically to make it work? The fare difference to move up to R was in the $2000s. The return is on AA metal