Hard to tell if this has already been reported, but I'm not seeing it and tonight's update didn't fix it.
Description:
I ran the beta branch last summer and collected all of the achievements in game tied to that content. I already had every other achievement completed from the base + DLC content, so this was strictly encompassing Westwoods, Ante Chamber, Mazerella, etc.
When the content officially released and I switched back to the default public branch, none of those achievements unlocked in Steam, itself. You can see the two side-by-side screenshots comparing in-game to Steam UI.
OS: Win11
Platform: Steam
Game Version: 1.14.111 (55804983R)