Guild Wars 2

I know miniatures are hidden “due to rising player population”.
But how miniatures exist, then are hidden, on a map with reached maximum players and queue, such as WvW Borderlands?

This does not make sense. I waited a queue of 37, entered map, had miniature for about 15 minutes, then it disappears with message “Miniatures have been hidden due to rising player population” when there was queue for the map all the time. So what rising player population is there, when the map already is full with maximum capacity reached, and queue created?

The message is misleading. Map population has nothing to do with culling; it depends only on how many resources are being used in the area close enough for you to see. It’s common for the area near BL spawns to be relatively quiet, which explains why you saw your mini when you entered the map, despite the long queue times.