When you check the open .map source with a text editor and search for all lines starting with: "classname" "trigger_
Are the triggers that don't work/inactive the last ones in the file?
Edit: Are you using portal textures to only render the parts of the map that are visible to the player?
If it is a limit, this might prevent the player from loading too many triggers at the same time.
Also, it will improve FPS.
https://wiki.zeroy.com/index.php?tit...uty_2:_Portals
http://modsonline.com/Tutorials-read-427.html