Cencord

I installed the portal gun mod on my server and when I play on it the mobs have like different textures. Like the creepers body is invisible but his head shows and the skeletons doesent have a leg. Sometimes the zombies texture is made out of many block textures like pistons, grass and dirt. And on the server it says: There was a problem getting field chunckSaveLocation from net.minecraft.server.ChunkRegionLoader I have been on the portal gun forum and I found no solution. Can someone help me?