Recurring events only sync from, and not to, GroupWise
From CompanionLink Support
Due to limitations of the GroupWise API (application programming interface), CompanionLink is only capable of syncing full series of recurring calendar events from GroupWise, but not to Groupwise.
More specifically, GroupWise sends recurring calendar events to CompanionLink as individual events, one for each occurrence, as opposed to giving us the specific pattern of recurrence. Further, we are not capable of editing or creating a recurrence pattern in GroupWise.
Given the above limitations of the GroupWise API, we only sync the initial occurrence of a recurring event if it does not originate in GroupWise. If you find that you need to define recurring events, you will want to do so from within GroupWise itself.