Yeah, I also have noticed this issue on my end as well. I always thought this was an game update bug. (Although I can get disabled lines for the passing since those are unnecessary with 8 survivors.)

Originally posted by Nicky Grimes:

I've been using this talker for a while along with ion's vocalizer.
The following lines I noticed aren't usable: Pain, Teamkiller, and other voice commands to do with P and some of character-specific lines.

I wanted to share this in case anyone who might be having the same issue noticed they couldn't do some lines in multiplayer.

To fix the issue, unsubscribe from the mod or slowly remove the talker scripts that conflicts with it.

All 8 Survivors Sourcemod

Rayman1103's Mutation Mod

Spawn L4D1 Survivors

Some more talker addons that i strongly recommend

Beel's Fixed and Expanded Talker

ChimiChamo's Talker Things

[Improved] Active Talker

Plugins

Survivor Set Flow Fix[forums.alliedmods.net]

Survivor Character Fixes[forums.alliedmods.net]

Force L4D2 survivor arms, names, icons[forums.alliedmods.net]

Credits

ihcorochris: suggesting certain lines
Xanaguy: helping and suggesting lines
Rayman: certain talker files and the inspiration to make this mod

Steakchelle:
the entire Dead Center elevator conversation