Juan José Mesbailer Arco

Sorry if I'm being confusing. When the fourth player joins, mobs already generated are still there, but no new mobs will spawn. However, as soon as we are three players or less again, mobs like phantoms are already coming down to attack, so it suggests that they were already there but just we could not see them and they couldn't harm us. Maybe they were not spawned at all, I don't know that for sure. But the point is that when we are 4 or more players, we can spend a hundred nights without sleeping and we won't find any monster in the night, phantoms would never show up, no fish or squids in rivers, no horses, cows or any other animal in the land. But the Nether is specially sad, you can loot a piglins fortress without problem because there are no piglins on it. We play on the highest difficulty level on survival mode. 

We're just using texture packs, but nothing else. We first encountered the problem with Clarity textures, then we created a new world with Natural textures pack and now it is happening again. The weird thing is that although we cannot see or interact with any mob or monsters, they are actually there, because if one of us leaves the game then they suddenly appear. Sometimes it also happens when one of us goes into the Nether. 

Sorry, I don't know how to extract the world from the xbox series x. However, we began with a new world now and we're facing the same problem. When the world reaches some size (don't know for sure but probably above 300 megabytes) mobs stop spawning. Oceans are empty, lands are empty and even the nether is empty, except when approaching to a spawner. We may spend 10 nights without sleeping and no phantoms show up, but then, as soon as anyone leaves the game and we are 3 player or less, all the mobs suddenly appear, as if they were already there but we cannot see them or interact with them.

Thanks for your reply. 

When we all (the six players) go together or separately to anywhere in the world there are no animals, no monsters, nothing but the small towns with villagers. For instance, if during the night 2 of us go into the nether, the 4 remaining on the overworld suddendly get attached by the phantoms, and monsters star to appear around our own town. The game without monsters doesn't make any sense, it is very frustrating and I've tried many ways to fix it (even we all unistalled the game and complements and then installed it all back again) but no success. Any ideas?