Factorio Forums

I'm trying to get all achievements in the game and the only one remaining is the Mass Production 3 achievement.
I was at about 2.2 M circuits and decided to play a bit on my modded game.

I opened the modded game, looked at the achievements and saw that I was at ~7.5 M circuits in modded mode.
After that I decided to continue with my unmodded game using the sync mods button to unload all the mods.
When I opened the achievements popup in my unmodded game I suddenly had 7.5 M circuits instead of the 2.2 M.
Now my achievements have also been synced to Steam and that also tells me I'm at 7.5 M circuits link

I got this same problem, but instead of one achievement, I unlocked 5 for building a rocket in a modded game and launching within the first 20 minutes trying out a design. When I reentered a non-modded game they all unlocked on steam. Sucks that I now miss out on the challenge.

Thank you for the report.
The bug was, that when saving the achievements, it was done while restarting the game, after the mod configuration changed to vanila, and the code just checked where to save depending on the current mod configuration.

It is fixed for the next version.