If you see that the changes made from Share are not getting queued in ActiveMQ or the Sync Service cannot request changes from subscription service, it means that ActiveMQ is down. In such an event, changes from Share cannot be synced to ActiveMQ, as a result both the synchronization and subscription services will be out of sync with Share. Also, the Sync Service will terminate.
Check the ActiveMQ, repository, and services logs. Restart ActiveMQ, the Sync Service, and the desktop to check if that resolves the issue.