All has been well with my achievements, but today I installed Advanced Access Manager and configured it a bit (the only thing I changed was to allow contributors to upload media files, nothing else).
Now subscriber level users are not getting any achievements (tested with multiple achievements with several dummy accounts). Contributor and above are fine and get their achievements. There are several settings on the AAA dashboard pertaining to this plugin, but all settings seem identical to contributor. Here's a screenshot of my actual subscriber settings. http://i.imgur.com/4fgUemD.png
Does edit_post have to be turned on for achievements to work for that user role? That's about the only thing I can figure, but it defeats the purpose of having a subscriber role if so.
I'm on multisite + buddypress + bbpress if it helps. Advanced Access Manager is activated network wide. Achievements for WordPress is activated per site basis.