Well, I thought this map would be easy to fix. Oh dear... was I in for a surprise >.<
It seems that this map was mostly just nav generated and that's it.

You need to know that zombies won't spawn automatically if there aren't any nav meshes. To do that you simply need to mark a walkable ground with a console command and generate it with another command which may take just a few minutes. Generated nav meshes aren't perfect, some nav meshes might be isolated and not connected with the rest and some might be missing.

That's were the level designer needs to step in and manually fix them but it looks like it never happened on this map. So it took me almost a week to stresst-test the whole map and I found way too many issues o.O but I still fixed them all. I hope the next map won't be that worst.

As I thought! This one was not as big as CE_Montclair but even worse on the navigation aspect. Same deal here. Just nav generated and be done with it >.< There were also a lot of unnessecary nav meshes. I deleted them and turned the file size to 19.9 MB instead of 22.16 MB. Might help the perfomance a bit :P

This map has the lowest nav issues so far! Good thing it isn't so big as the other maps or I wouldn't made it in time since I worked on an update for HotZ this week :)

Update - 06-17-2016 | CE_Harvest
After working on Biotec I noticed that the nav file size of Harvest is much bigger than Biotec. To my surprise there are a hell a lot of nav meshes outside the playable area which does not serve any purpose and after deleting them all I got 14.55 MB instead of 25.16 MB!

Biotec is a pretty big map with a lot of different rooms. It was time consuming to check on every room with the same layout over and over again but I did it before I fell asleep lol.
Unfortunaly the trees on the roof aren't fixable with nav meshes. I have tried it out but zombies can't jump so there is nothing I can do about it. The level designer needs to seal those trees! The nav file size of Biotec is 16.19 MB and I manage to decrease it to 12.48 MB :)

One of the biggest map in Contagion with complex random routes. Took me a while to finish this and I hope that I haven't forget a section :S The nav file size was the biggest from all of the maps with 30.84 MB but I manage it to shrink it 15.99 MB by optimizing the nav meshes :)

The first official map ever created for Contagion is RPD. This map has a long history and is one of the most polished Contagion maps. Over 20 level designers had worked on this map and kickstarter rewards aka "wanted RL pictures" were implement into this beast. The nav files size is just 1.45 MB! Smallest file size ever but I still manage to optimize it to 1.04 MB :)

The first and last custom map that joined in with the stock maps made by ex Contagion Lead Leveldesigner Joure aka DeRaNgEr. This map is small since it is designed to be a hold out map similar to the flatline gamemode. Well, I still found some nasty nav issues mostly inside the house. The nav file size is just a little over 5MB so there isn't much to optimize.

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I have documented every nav issue and marked them properly. Every issue is uploaded as a screenshot on this workshop page. Please post here if you happen to find any new issue on the mentioned maps above while playing with this addon and I will take a look at it. Thx!