Member Syncing works by scraping the list of staff members in your group and syncing them with Hyra. If your member list are hidden, your group members activity won't get credited and your workspace won't get synced.
Try following the steps below regarding member syncing:
Go to your community and click the three-dots on the top-right corner to view more options.
In Configure Community, click the Settings page in the sidebar to go to Community Settings.
Under Community Settings, go to Community Profile and enable Community member list publicly visible.
Once done, Hyra will take care of the rest and sync your workspace with your group members.