[Shadowysn]

Edit: New game update has resolved this. Don’t use this gamedata anymore.

Haigen said SetClientInfo had a change in the InfoChanged offset due to the recent Dedicated Server update, so Sourcemod's official gamedata changed to use this offset.
So I think this change may be the reason why local servers are crashing; the update that changed this offset was only pushed for Dedicated Servers, so any plugin that used SetClientInfo would crash in local servers.
The local game client didn't receive this update that changed the offset, and Sourcemod usually doesn't put out much support for local servers despite being able to be used.

For local server hosters who are getting crashes with this plugin, create a new folder in left4dead2/addons/sourcemod/gamedata/sdktools.games called custom and then put this file inside it.
Should work with SM 1.11 and hopefully SM 1.12.
Just make sure to remove the file if an update to the game happens one day, or you might be stuck with outdated offset crashing again.