Hi I've got a question for Mobspawn. I play on the AG3 have a Mobfarm but it only spawn mobs when I'm standing right with him. My main processing is 45 blocks away and when I'm there no spawn mobs. Sorry for my bad English
Vanilla mechanics. As far as I know the minimum distance is 25 blocks (almost the height of your mobspawner, if it is a vanilla one) BUT there is a maximum that is like 40-45 blocks (not sure of the exact distance, check mcwiki for more details)
Then, this is strange. I suggest you to change water with conveyor belts, so you can let enderman spawn with no problems and later on get a chunk loader or, better, a spot loader.
If I remember correctly they don't move unless you are within 32 blocks of them, so it might be too far out, especially if the 42 blocks is only the horizontal distance, if you add the 23 vertical distance for drop , the mobs are over 64 blocks away at the least.
This server seems to have chunk processing disabled if anyone is furher than 2 chunks (32 blocks). Enable chunk grids and if your processing really is 2 chunks afar, it wont work. So the loaded chunks are - chunk you are on, the ones next to you (8) and the ones next to those (16). A total of 25 chunks. I also found this out the hard way.
we use the default vanilla, spigot, mcpc settings according to chunks, as if we would not you would get chunk loading issues. Code: #Minecraft server properties #Thu May 29 15:44:05 CEST 2014 generator-settings= op-permission-level=4 allow-nether=true level-name=world enable-query=false allow-flight=true server-port=25563 level-type=DEFAULT enable-rcon=false force-gamemode=false level-seed= server-ip= max-build-height=256 spawn-npcs=true white-list=true spawn-animals=true hardcore=false snooper-enabled=true texture-pack= online-mode=false server-id=unnamed pvp=true difficulty=3 gamemode=0 player-idle-timeout=0 max-players=80 spawn-monsters=true generate-structures=true view-distance=10 spawn-protection=16 motd=\u00A71M\u00A72Y\u00A74M\u00A7f-\u00A72Agrarian Skies +
Maybe the defaults act that way then? No machine runs if you have 2 or more chunks between you and the machine, tested on AG1. The visual chunk loading is around 7-9 chunks in radius i believe. Example: Put a TE furnace running, go 3 chunks further, wait 5 minutes, go back, still at same progress as you left it.