Totara 2.2.18 is a "snapshot" release containing bug fixes.
Here's the 2.2.18 changelog:
Release 2.2.18 (7th May 2013):
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New features:
T-9460 Add learning plan report source
Improvements:
T-10713 Move changelog into PHP file to prevent version identification via the web
T-10193 Set minimum width on tinymce editors
T-10117 Make Totara sync more verbose while running
T-10316 Show warning message if session is overbooked
T-10573 Allow embedding media in program summary and endnote
T-10702 Show email next to user name when enrolling individuals
T-10408 Add clear Totara Sync log functionality
T-10662 Add firstaccess column to a user report source
Database Upgrades:
T-10471 Migrate issued certificates when upgrading to 2.2
Bug Fixes:
T-10373 Redirect to courses page if unable to enrol in a course
T-10380 Fix status completion required when updating scorm
T-10628 Fix undefined variable errors in Messaging settings
T-10403 Fix hierarchy custom text and file fields Postgres error
T-10637 Hide audience functionality in courses from users without permissions
T-10463 Fix formatting in Site Log report export
T-10461 Fix Course Completion report export
T-10352 Set correct user in createdby field of signup status updates
T-10617 Fix corrupted site logs excel export
T-10277 Fix the amount of days in a year in programs
T-9446 Fix facetoface sessions duration output
T-10416 Fix rules issues in cloned audiences
T-10361 Show sidebar on Learning plan template component tab
T-10574 Fix display of images in program description
T-10626 Ensure report builder handles checkbox custom field default