We're running on the latest spigot build, and we noticed a bug in which instead of sending a chunk with no blocks in it (the end or any empty chunk) - The server will send a special packet that is misinterpreted by the client. To unload chunks, send this packet with Ground-Up Continuous=true and no 16^3 chunks (eg. Primary Bit Mask=0). (http://wiki.vg/Protocol#Chunk_Data) - The server sends that for end chunks, when it should be sending one section at the bottom with just air,

This issue causes blank chunks in the end to act weird and force unload when players are still in them etc