Where in either Bambu Studio or on the printer control panel can you determine which right nozzle is being used in the extruder?
In the “Print Plate” window, Bambu Studio shows the filament mapping (right vs left nozzle). If you have an AMS connected to the right nozzle, the filament mappings for the right nozzles would have two sections listed by color. The top one would say “A#” (the AMS slot being used) and the bottom would say “R#” (the nozzle number that the printer plans to use).
(Not in front of my computer right now to capture a screenshot.)