99,9% Possible fix:

1) Unsub from all of the 5 Content Packs.

2) Launch Garry's Mod: Disable (NOT UNINSTALL) all your addons, this is necessary to make extra sure. There is an option for that, just click on Disable All.

3) Restart Garry's Mod, open the console then type the following command:

menu_cleanupgmas

4) Exit Garry's Mod. Subscribe to the 5 Content Packs again.

5) Load the map and see If everything loads correctly and you can see all of the assets/textures/models.

If so, you can now re-enable all the remaining addons. If you see the problem persists, means there is something else to it and you'll have to find what it is. Most likely another addon.