Duh. I knew that for Economy but I overlooked it for WT+. I wonder if this will ever be harmonized (or should I say harmonised) with BA. For all the complaining about BA surcharges, at least BA lets discounted WT+ fares be upgraded with EC miles (or whatever they're going to call them going forward).

The full fare WT+ requirement still doesn't explain why AA agents have such difficulty finding an upgradeable WT+ fare.