Ok, so a little FAQ first regarding the workaround. Skip ahead to next section if you don't care

Q: When's this possible bug getting fixed?
A: Not sure.

Q: What causes this bug and is there a way to prevent it from occurring?
A: Again, not sure. In my experience and with some other players it didn't pop when we got Speedster as our last achievement.

Q: Will this workaround flag my account for cheating or something?
A: Simply put, I can't see why it would because you're manipulating game code to a VERY minor degree and they allow modding on the game explicitly anyway. And it's a singleplayer game with no microservices.

Q: Could I use something like Steam Achievements Manager (SAM) to achieve the same goal?
A: Sure, go ahead if you prefer that. I personally have never used that on my main account and I've never done a workaround for a glitched achievement, but this at least means it's running directly in the game and not some 3rd party app.

Q: Can the workaround be reverted?
A: Maybe, but why bother? You can use SAM for that or use something in the game code that would remove an achievement if there exists a method like that. But again, I see no reason except for testing purposes or if you want to get it 'legitimately' when it gets patched.

Q: Is there anything malicious in the workaround?
A: No. I'm not nearly savvy enough to create a script running in your game that will steal your credit card information or destroy your operating system.
If you really want to, just compare the file with your original file in WinMerge or some online text comparison editor and you'll see it's literally just a method call to a method that exists in the game code and nothing else. It's simple and nothing ingenious.

Q: Can we just get to the workaround, I don't care about FAQs
A: Okay then... Just putting it out there to prevent repeated questions (hence, FAQ).

GDrive Link to file[drive.google.com]

Close Amnesia: Rebirth first if it's running.

Go to your game's folder.
Easiest way is to go in Steam Library, right click on Amnesia Rebirth, then click Properties, Local Files tab, then click on Browse Local Files.

It's located in <SteamLibraryLocation>\steamapps\common\Amnesia Rebirth

Then navigate to \script\custom\modules

Find the file named MenuHandler.hps and make a backup copy of it.

Delete the original MenuHandler.hps

Copy the file you downloaded from Google Drive[drive.google.com] (also named MenuHandler.hps) into the modules folder mentioned above.

Run the game.

The achievement should pop by the time you hit the menu

You can then close the game and delete the downloaded MenuHandler.hps file and rename your backup copy so that it's back to its original name.

Thanks for using this guide and I appreciate any constructive feedback.

Let me know if it's worked for you!

Also, comment if you know of a way to get Reborn without using any workarounds like this.