Hey everyone,
in the last patch we did, we accidentally broke the Steam Achievements.
Thanks to a bug report, we could track down the problem and have deployed a patch that should solve the problem.
Sorry for any issues this caused.
EDIT: We just realized that by fixing the Steam Integration, progress you made from January 6th until now has been reset. Saving & loading should be fixed now. We're really sorry if you lost any progress because of this.