So I have this weird problem. No mobs spawn naturally when players enter a certain group of chunks. There is an area next to the spawn point (spawn point is incluided but not the center of the area). When a player is inside the area mobs stop spawning (server-wide, natural spawn - mob spawners work). When he is even 1 block outside of it - mob spawn is normal. If I reboot the server, mob spawn is normal for a while, then the problem stars again. And its the same area(a few chunks) not a random new one. What do you think is causing it? Also feel free to ask questions about the area and whats inside it because I don't think there is anything unusual inside those chunks.