I have played this mod over a dozen times and never had a problem. This time the elves disappeared and I was left alone to get rid of the orcs. I searched the posts, but could not find any reference to this particular problem with the mod.
I went to kill the balrog in the lower right corner of the map. When I left the holu area to kill the balrog, there were about 20 elves in the holy area. After I killed the balrog, I when back to the holy place in the center and there were no elves. I finished killing off the orcs and other two balrogs. Before I left, I searched the entire area, but no elves were found. While searching for elves, I checked all the items left by the dead. I found three bows from elves killed by orcs in earlier battles. But I found no items from the 20 elves that were there. I do not know what happened to them.
Tom