After running a server since the first beta updates, getting the below error with the mod installed even with no one online, error goes away after removing Academycraft

Error doesn't resolved itself by installing beta 6

Description: Exception ticking world

java.lang.IllegalStateException: TickNextTick list out of synch
at net.minecraft.world.WorldServer.tickUpdates(WorldServer.java:691)
at net.minecraft.world.WorldServer.tick(WorldServer.java:223)
at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:756)
at net.minecraft.server.dedicated.DedicatedServer.updateTimeLightAndEntities(DedicatedServer.java:397)
at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:668)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:526)
at java.lang.Thread.run(Thread.java:745)

A detailed walkthrough of the error, its code path and all known details is as follows:

-- Affected level --
Level name: world
All players: 0 total; []
Chunk stats: ServerChunkCache: 45 Drop: 0
Level seed: 4655362806987790371
Level generator: ID 00 - default, ver 1. Features enabled: false
Level generator options:
Level spawn location: World: (0,0,0), Chunk: (at 0,0,0 in 0,0; contains blocks 0,0,0 to 15,255,15), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Level time: 0 game time, 0 day time
Level dimension: 0
Level storage version: 0x00000 - Unknown?
Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false

Does it affect gameplay?

Server can no longer run for more then 2-5 minutes before crash.

Even running it locally no longer works.

I'm a bit confused about the timepoint that this bug appears. Do you mean that the bug exists ever since beta1, and still exists now?

Closing as no further updates.