Upstream Paper

sources/src/main/java/net/minecraft/server/Chunk.java

@@ -982,6 +982,8 @@ public class Chunk {
                     }
                 }
                 // Spigot End
+                entity.setCurrentChunk(null); // Paper
+                entity.entitySlice = null; // Paper
 
                 // Do not pass along players, as doing so can get them stuck outside of time.
                 // (which for example disables inventory icon updates and prevents block breaking)

sources/src/main/java/net/minecraft/server/Entity.java

@@ -85,7 +85,7 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper
     private static final List<ItemStack> b = Collections.emptyList();
     private static final AxisAlignedBB c = new AxisAlignedBB(0.0D, 0.0D, 0.0D, 0.0D, 0.0D, 0.0D);
     private static double f = 1.0D;
-    private static int entityCount;
+    private static int entityCount = 1; // Paper - MC-111480 - ID 0 is treated as special for DataWatchers, start 1
     private int id;
     public boolean i; public boolean blocksEntitySpawning() { return i; } // Paper - OBFHELPER
     public final List<Entity> passengers;
@@ -345,6 +345,7 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper
         this.locX = d0;
         this.locY = d1;
         this.locZ = d2;
+        if (valid) world.entityJoinedWorld(this, false); // Paper - ensure Entity is moved to its proper chunk
         float f = this.width / 2.0F;
         float f1 = this.length;
 
@@ -990,6 +991,7 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper
         this.locX = (axisalignedbb.a + axisalignedbb.d) / 2.0D;
         this.locY = axisalignedbb.b;
         this.locZ = (axisalignedbb.c + axisalignedbb.f) / 2.0D;
+        if (valid) world.entityJoinedWorld(this, false); // Paper - ensure Entity is moved to its proper chunk
     }
 
     protected SoundEffect ae() {
@@ -1792,7 +1794,7 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper
      */
     public Chunk getCurrentChunk() {
         final Chunk chunk = currentChunk != null ? currentChunk.get() : null;
-        return chunk != null && chunk.isLoaded() ? chunk : null;
+        return chunk != null && chunk.isLoaded() ? chunk : (isAddedToChunk() ? world.getChunkIfLoaded(getChunkX(), getChunkZ()) : null);
     }
     /**
      * Returns the chunk at the location, using the entities local cache if avail

sources/src/main/java/net/minecraft/server/World.java

@@ -1960,7 +1960,7 @@ public abstract class World implements IBlockAccess {
                 this.getChunkAt(entity.ab, entity.ad).a(entity, entity.ac);
             }
 
-            if (!entity.bD() && !this.isChunkLoaded(i, k, true)) {
+            if (false && !entity.bD() && !this.isChunkLoaded(i, k, true)) { // Paper - Always send entities into a new chunk, never lose them
                 entity.aa = false;
             } else {
                 this.getChunkAt(i, k).a(entity);