It's working for me. I'm not sure you're letting the round start properly in your testing. The entities are not loaded from the script until a round starts.
In the console after a round starts, you should see something like this in blue text:
Weapon/ammo placement script found, attempting import...
Reading settings from script...
Removing existing player spawns
Removing existing weapons/ammo
Importing entities...
Spawned 176 entity found in script.
Weapon placement script import successful!
If that's not there, the game is probably still waiting for players.
Make sure you either set ttt_min_players 1, or spawn a bunch of bots to get sufficient players to start a round after loading the map.