The matchmaking/queue system for PVP pet battles is notoriously buggy I wanted to see how many people have issues and anything they have noticed that causes it.
The most common bug is that the queue either pops for a split second or just never pops. After this when you try to requeue an error message appears stating that you are already queued up.
This obviously has implications for anyone queuing up as their perception may be that despite wanting to battle they are not actually queued.
I don’t know what causes the bug but it could affect a whole battlegroup if one player can unwittingly do it several times.
The only way to unbug the queue is either relog or start a pve battle but even then it doesn’t always work.