Achievements Earned but Not Unlocking

I’ve just completed the Hundred Year’s War campaign, achieving both the campaign completion Achievement as well as the “Careful Cannons” one for not losing any artillery in the final scenario. It SAYS in-game that I achieved them, but for some reason, STEAM doesn’t think I did.

I think there was a server outage or something while I was playing, so it didn’t register properly, but I quit the game and then rebooted it, and even played the scenario through completely a second time, and it’s still not working. What do I do?

I apologize for double-posting, but it has been a while and I still haven’t figured out how to fix this on my own. I’m not comfortable playing the game further until I’ve fixed this and I’m worried uninstalling and reinstalling the game will wipe all my progress without fixing the achievements not unlocking.

What should I do?