It was generated on the night version, however since the other two versions of the map have absoplutely no geometrical differences (to my knowledge) the nav file works exactly the same on them as well. All you have to do is take the nav file I provided here, copy it, paste a duplicate and rename it to either "gm_kss_metropolis.nav" or "gm_kss_metropolis_sunset.nav" (depending on which map you want the nav to load up for). Valuable for nextbox npcs that require a nav mesh to function, such as nextbox zombies 2.0 and others.

(.nav files should always be placed in the maps folder of your garrysmod directory, even if the workshop .bsp is not located there, it will still work fine.)

https://www.dropbox.com/s/b20di8vul2g0rxi/gm_kss_metropolis_night.nav?dl=0