Bug Fixes:
- Fixed an issue where Horde Mode achievements (Waves, Zombies, Boss, Cockroach, Points, X2, Health, Ammo) could fail to unlock if the cumulative counter had already passed the required threshold in a previous session. All achievement checks now trigger correctly regardless of when the milestone is reached.
Update Notes - 1.6 - Achievements Fixed
Source: Steam Community (opens in a new tab)