Enum WorldSceneQueueReason
Why a client is waiting in the WorldServer's scene-routing queue.
public enum WorldSceneQueueReason : byteFields
Every running instance of the target scene is at capacity.
The character's combat-logout body is still standing in a specific scene instance, and only the scene server holding it can hand it back.
A scene instance has been requested and is still loading on a scene server.
Remarks
The three waits look identical to a player — a loading screen that is not progressing — but they have very different causes and very different expected durations, and only one of them is the server being full. Naming the cause is the difference between "the game has hung" and "the game is waiting for something specific".