Just to advise. I updated from Achievement 3.4.1 to 3.5 last night.
Right after the update, my posts that show achievements stopped processing the shortcode used in the achievements to format the display.
WP: 3.7.1 (Multisite) (Theme is Razor from Themeforest)
Uninstalled 3.5 and reinstalled 3.4.1 and everything was back to normal. (shortcodes processed properly).