After a few hours of investigation, it's likely that workshop system is flawed. The map, when loaded without workshop system, (that is, when stored in local drive) works fine and dandy. The problem rises only when I upload the file onto workshop.

The source engine has a 'path' command allowing you to observe which game data you are loading. When used on this map, the command outputs that the map is loading only HL2 base content, despite having the Game Inclusion File stating that the map should load EP2 and EP1 files, also.

The path command outputs that the game is indeed loading EP2 files when playing the original EP2 maps. (The EP2 maps do not have Inclusion Files by default as their game datas are managed by the Game Definition Files)

In order to test this theory more scientifically, I have extracted one of the EP2 map file and uploaded it onto workshop with corrosponding Inclusion File. To my surprise, the game didn't load EP2 content; the map was full of missing textures and models, even through all I've done was uploading it onto workshop!

Therefore, I (to a certain degree) suspect that it is workshop making things wrong. I'm yet to ask a developer of this problem.

There is still a few more suspects, however. One is that the developers changed the way Inclusion Files works. This indeed has happened once, where they changed Lost Coast's inclusion tag, "lost", to "hl2lc", rendering Lost Coast unplayable for a while. However, I doubt they'd do similar mistake again.

Or it just could be me, doing the uploading process wrong. Maybe different rules apply when it comes to workshop and I'm the only one who doesn't know that. I probably should contact a developer soon so I can consult him about the problem.

Fixed the f-ing missing textures/errors.
.. Wait, it didn't...

Attempted to fix the texture/models bug, miserably failed.

Now truly compatible with the new Synergy update. This is third time I'm trying to fix the stupid compatible issue.

Fixed .INC file error which caused some people to see missing contents.
Added the raw .VMF, .PRT, .LOG files of the map to help players have fun tweaking the map. You are not allowed to distribute these files however.

Updated to accommodate the new Synergy update.
Added HL2 EP1 as game requirements.

Removed the func_precipations.
Vending machines are now functional.
Cut the second city part.
Ceiling turrets will not die with player's weapons.
Nerfed the getaway vehicles.
Added Barney the Barnabus in honour of Sven Co-op.
Red-glowing buttons can be triggered from a long distance by damaging at it.
Removed the feature where enemies could attack and destroy the device.
Better optimization by removing a few NPCs in the map.

Initial Release