Lost one AirPod Pro — but “find my“ thinks it is together with the other one!

If your AirPods or AirPods Pro are separated from each other, you see only one location at a time on the map. Find the AirPod or AirPod Pro that you see on the map and put it in its case. Then refresh the map and find the other one.

If your AirPods, AirPods Pro, or AirPods Max are out of range or need to charge, you might see their last known location, "No location found," or "Offline." You also won't see the location for your AirPods or AirPods Pro if they're inside their Charging Case.

If you see "No location found" or "Offline" under your AirPods, AirPods Pro, or AirPods Max, you can't play a sound to find them but you might be able to get directions to the location where they were last connected. If they do come back online, you'll get a notification on the iPhone, iPad, or iPod touch you use them with.

(from Apple Support)