Max payload after changing aircraft

I'm playing R6, and if I change an aircraft operating any route from the Flight List tab in the route details screen, then change to the Add Flights tab, the Max payload for all available aircraft is 330 pax. This is regardless of whether the aircraft can actually handle 330 pax or not.

Aircraft that should be able to handle more than 330 pax are shown in red bold.

Refreshing the page, or clicking Research route reloads the data which then shows the correct maximum payload for all available aircraft.