Steam sessions can not return player count

Are you possibly changing the server name in any way? I noticed when you update the session even if you pass in the same name again it will detect as you “changing it” which will make it not appear. if that might be your issue then update your session by getting settings then modifying only what you need modified.
image
something like this image where you get the already existing settings and then only modify the player count key and pass the same server name as you are not changing it.