Guild Wars 2

Last night I finished the last map I needed to get 100% world completion. Finished the last heart and got the map reward and the 100% reward. Didnt see the achievement pop up and was thinking wait this is odd but I had to get to bed for an early day of work. After work I went through and grabbed the last two points of interest to fill in all of the pois listed in the counter. Afterwards I did not receive the achievement which is still listed as 99 of 100. Not certain what I missed or what has happened here

You can try visiting (or re-visiting) the Chantry of Secrets. That often clears up the issue.

http://wiki.guildwars2.com/wiki/World_completion#World_completion

Good luck.