Nether portal not working as intended

Moderator Edit:
After patch 1.8.1 certain nether portals will become desynched when multiple entities or players pass through them. If two players pass through a portal in rapid succession they will enter into the nether at an unrelated, unlinked portal, however if they pause for a few seconds between entering the portal they will arrive in the nether at the correct portal. Occasionally full client-desynch on multiplayer will occur, causing chunks around the client entering the overworld from the nether, not to load requiring client reconnect.

These portals have been in place for a long time and no additional portals have been built nearby to interfere, and are not within range to create a dual-destination portal. This behavior was not observable in 1.8, but can be observed in 1.8.1.

After patch 1.8.1 a specific nether portal stopped working in my world which kicks everyone off the server when 2 or more mobs enter the portal. In addition to that, if you throw any item through the portal and then go through said portal, the portal takes you to a completely unconnected nether portal far away. Also, if you throw two items into the nether portal, one at a time, it kicks everyone off the server and gives the "server closed" error. However, if you do not throw anything through this specific nether portal, it takes you to the correct place. I haven't touched these portals in over a month and it all started on Nov. 24th. after the 1.8.1 patch. I cannot give you a crash report, only logs because I and everyone else keep getting kicked off the server when 2 or more mobs go through it, the game doesn't crash but there is definitely a bug. The portal is used for a mob farm. I cannot recreate any of these results with any other portals in my world. It is only this specific portal. The portal is connected correctly, I know how all of the nether portal linking mechanics work and they all worked perfectly until 1.8.1 and I have no clue as to why this is happening nor how to fix it.

Here is a crash report of this world copied into a single player world from my minecraft realm server. The problems still occur in my single player as they do in multiplayer server.

---- Minecraft Crash Report ----
// Ouch. That hurt :(

Time: 11/30/14 10:22 PM
Description: Ticking entity

java.lang.NullPointerException: Ticking entity
	at ayv.f(SourceFile:263)
	at are.b(SourceFile:123)
	at are.a(SourceFile:59)
	at sp.a(SourceFile:514)
	at wx.c(SourceFile:1749)
	at wx.K(SourceFile:303)
	at xo.K(SourceFile:176)
	at xq.K(SourceFile:157)
	at wx.t_(SourceFile:266)
	at xo.t_(SourceFile:1265)
	at xq.t_(SourceFile:211)
	at afm.t_(SourceFile:32)
	at aqr.a(SourceFile:1407)
	at qu.a(SourceFile:600)
	at aqr.g(SourceFile:1385)
	at aqr.i(SourceFile:1278)
	at qu.i(SourceFile:478)
	at net.minecraft.server.MinecraftServer.A(SourceFile:608)
	at net.minecraft.server.MinecraftServer.z(SourceFile:532)
	at cyk.z(SourceFile:155)
	at net.minecraft.server.MinecraftServer.run(SourceFile:448)
	at java.lang.Thread.run(Unknown Source)


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

-- Head --
Stacktrace:
	at ayv.f(SourceFile:263)
	at are.b(SourceFile:123)
	at are.a(SourceFile:59)
	at sp.a(SourceFile:514)
	at wx.c(SourceFile:1749)
	at wx.K(SourceFile:303)
	at xo.K(SourceFile:176)
	at xq.K(SourceFile:157)
	at wx.t_(SourceFile:266)
	at xo.t_(SourceFile:1265)
	at xq.t_(SourceFile:211)
	at afm.t_(SourceFile:32)
	at aqr.a(SourceFile:1407)
	at qu.a(SourceFile:600)
	at aqr.g(SourceFile:1385)

-- Entity being ticked --
Details:
	Entity Type: Guardian (afg)
	Entity ID: 108683
	Entity Name: Guardian
	Entity's Exact location: 202.00, 24.00, 288.00
	Entity's Block location: 202.00,24.00,288.00 - World: (202,24,288), Chunk: (at 10,1,0 in 12,18; contains blocks 192,0,288 to 207,255,303), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Entity's Momentum: 0.00, -0.01, -0.09
	Entity's Rider: ~~ERROR~~ NullPointerException: null
	Entity's Vehicle: ~~ERROR~~ NullPointerException: null
Stacktrace:
	at aqr.i(SourceFile:1278)
	at qu.i(SourceFile:478)

-- Affected level --
Details:
	Level name: Minecrack-2
	All players: 1 total; [qx['Zaraxas'/2898, l='Minecrack-2', x=1619.70, y=25.00, z=2316.91]]
	Chunk stats: ServerChunkCache: 4739 Drop: 0
	Level seed: 8054171159163673492
	Level generator: ID 00 - default, ver 1. Features enabled: true
	Level generator options: 
	Level spawn location: -68.00,64.00,256.00 - World: (-68,64,256), Chunk: (at 12,4,0 in -5,16; contains blocks -80,0,256 to -65,255,271), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
	Level time: 34679347 game time, 34834788 day time
	Level dimension: 0
	Level storage version: 0x04ABD - Anvil
	Level weather: Rain time: 79442 (now: false), thunder time: 88656 (now: false)
	Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false
Stacktrace:
	at net.minecraft.server.MinecraftServer.A(SourceFile:608)
	at net.minecraft.server.MinecraftServer.z(SourceFile:532)
	at cyk.z(SourceFile:155)
	at net.minecraft.server.MinecraftServer.run(SourceFile:448)
	at java.lang.Thread.run(Unknown Source)

-- System Details --
Details:
	Minecraft Version: 1.8.1
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.7.0_45, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 1390454248 bytes (1326 MB) / 3170893824 bytes (3024 MB) up to 5726797824 bytes (5461 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx6G
	IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
	Profiler Position: N/A (disabled)
	Player Count: 1 / 8; [qx['Zaraxas'/2898, l='Minecrack-2', x=1619.70, y=25.00, z=2316.91]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.