Valheim 1.0 Achievements: Why They May Not Unlock
Check Valheim 1.0 achievement tracking, old boss kills, permanent cheat flags, marked items, and world modifiers before troubleshooting a missing unlock.
Quick Answer
Valheim achievement tracking starts when you install 1.0, so pre-update boss kills do not automatically unlock achievements. Check whether the character or world has a permanent cheat flag, or whether marked spawned items are causing a temporary cheated state. Removing all marked items can clear the temporary state; it does not remove a permanent flag.