Solved Server world statistics

Honestly I feel a little strange posting a question of my own here instead of a reply. Well, the time has come!

I think it was a couple months ago when I was fiddling with the server's worlds, but I didn't pick up on the problem until just lately. On the server I run, statistics cannot be achieved by players, and from this error message (seen when I start the server) I think I know why, I just don't know how to change the setting.

Error Msg:
[Server] WARN *** WARNING *** stats.disable-saving is true but stats.forced-stats.achievement.openInventory isn't set to 1. Disabling stat saving without forcing the achievement may cause it to get stuck on the player's screen.

Before anyone who only skims this post replies "oh, just add announce-player-achievements=true in server.properties" I must reiterate again that it isn't stifling the message, it is not even giving the player the achievement.

More Info:
- problem persists for all groups
- previously-attained achievements are still in the client's "achievements" window
- to repeat, getting an achievement (i.e., chopping wood) is not possible and does not appear on the client's screen or achievement list
- to confirm, I'm talking about built-in minecraft achievements, not custom/plugin ones

 

Update: I found the problem. It wasn't a corrupted world file as I originally assumed, but something that happened when I decided to start using spigot. In the spigot.yml:
disable-saving: true

refers to the saving of achievements