UPDATE: PSA I found that Logical doesn't have access to the TUVONG map files anymore so any issues can't be resolved sadly, however I still think if there is enough people explaining the issues with the zombie targeting, that the issue might boil down to a Pre-Processing map error with the Zombie spawns because of how they target the host player and eventually will not despawn at the ends of the zip lines if a player goes down, only when the downed player completely dies do the zombies despawn unless the other player makes there way to the surface beforehand.

So I played this map solo and completed the Main Easter Egg for the Gold Helmet and the Buyable ending, great solo map by the way. So When I first tried playing with my friend I hosted and his game wouldn't finish loading in so we switched hosts. When he was host the game ran fine up until the point where we got the the power steps for the Easter Egg, *i.e. The Zipline in the cave might have to do with the "targeting issue" where the zombies only target the host player. Up until the point where I jumped down before my friend to start the power sequence on the EE; zombie targeting was normal. When we separated using the zip line I noticed how zombies stopped spawning in normal amounts in the Atrium General Area; and when they did, they only broke the barricades and then proceeded to stand still after stepping out of the windows and not move until the HOST player dropped from the surface into the BUNKER section of the map. From this point on for the rest of the game the zombies would not target me and only focus the host and repeated the process of standing still I just explained. So, besides that; we continued to do the Main Easter egg steps, unlocking the doors with the key, crafting the other items, etc. We were able to do the lockdown step where we farm the mimic blood and insert it into the Reactor, once we reached the Elemental step that you use the bows for there were no Elemental Orbs around the map. I also made sure I asked my friend if he was able to see the main parts of the EE such as the ORBs and the mimic blood step. Just before starting the mimic blood lockdown sequence we were able to draw the mimic to the LOCKDOWN CHAMBER and it wouldn't automatically get pulled into the chamber once it was right next to it and continued to only target the host. Although I was able to activate the step from the panel REGARDLESS and we proceeded to get the MIMIC BLOOD and insert into the REACTOR. I made sure to double check we did all the steps right for the EE and we assumed for a while that the Main EE was only available for SOLO since I had completed it just an hour before he and I played together. I hope this explanation of what we went through can help you fix the issues some of these other players seem to be experiencing. If you need another player to help test this map or others for issues I'm available whenever.

Notes from playing solo:
So in my time playing solo I was able to complete the Main EE and everything and also messed around a lot with the Zip lines. Some notable things to mention are that the zip line by the WATERFALL and STAMINUP is a DEADZONE on the surface part if you stand in that doorway corridor just before the drop down. i.e. Zombies won't spawn at all, only when you exit the corridor in front of STAMINUP roughly in that area is when Zombies will start spawning again, but if you walk BACK into the CORRIDOR where the DEADZONE is it will, again, stop the spawning entirely.
However, the CAVE SIDE of the map the surface corridor before the drop down is quite the opposite and is a GREAT spot to farm and be safe. I noticed very quickly the mechanic of how the zombies DESPAWN once you drop DOWN the zip lines and go UP the zip lines. I played around with this for a long time and got to like round 50ish with ease abusing this and using the GOLD HELMET to just play, great design for long game play and party style game play. So from a GAMEPLAY POV the SOLO version of this map is as close to PERFECT as I could imagine as a long time zombies player. However the issue with the HOST targeting is making a lot of people probably not want to share this map and the issue itself seems like it could be a simple fix. I'll stay active on this topic, just let me know if you have anything you want me to do or any questions.

<3 - J