Valve has released an update for Left 4 Dead (the first one, mind you). This update should patch any achievement progress you might have lost when downloading any of the latest DLC, specifically ‘The Sacrifice’. The update also fixes the glitchy ‘Sacrifizzle’ achievement.
Hopefully all progress lost because you picked up ‘The Sacrifice’ will be restored; however, Valve states on its Left 4 Dead Blog that in a few cases, some achievement progress might not be possible to recover.
Below is a full list of the bugs that have been patched.
• In Versus mode Tanks will spawn in stasis until a human player takes over. Tanks in stasis are invisible and invulnerable, and won’t move or attack.
• Tank speed is no longer reduced when on fire.
• Allow players on the Infected team to manually spawn during finales.
• Added a vote option to toggle All-Talk.
• Special Infected that causes a Survivor to stumble into a “ledge hang” situation will receive 50 points.
• Bullets that first pass through an infected character before striking a Survivor are now ignored as friendly fire.
• In Versus mode car alarms will now trigger anytime a Special Infected pulls or stumbles a Survivor into an alarm car.
• Survivor Bots no longer try to melee exploding barrels out of their way.
• Fixed the Sacrifizzle achievement.