I noticed that the zombie spawn time should be lowered (as in sooner) by about 3-5 seconds. Sometimes a human will pick up the ring and a few seconds later they would be chosen as mother zombies. it doesnt happen all the time but it does sometimes end up making the person who pick up the ring to drop the ring down to the floor so that it is now inaccessible. The one important goal on this map is to keep the ring bearer alive as the final hold point is extremely hard without it. i think just setting the zombie spawn timer back by a few seconds should be able to fix this problem. Edit: TLDR read the bold text.