Sometimes already created rooms are not visible in the lobby.

hello. We are running a game based on Unity 2020.3.38f1 on PUN2.40 (Realtime + Chat).

It's not a problem that usually happens often, but sometimes there is a problem that the room is not visible in the lobby even though there are users who actually play in the already created room.

A detailed description of the problem.

1. Someone creates a room and the room is appeared in the lobby.

2. Sometimes created rooms disappear from the lobby. But in the room, people are playing the game and the room is not full.

3. After some time, the missing room will be displayed in the lobby again. And we can enter the room normally.

Due to this problem, users can't meet each other sometimes, so we're having a hard time. Can we get some help with this?

We used an English translator. Please forgive any awkwardness in the sentence.