If you are using Autodesk Revit 2016 and Collaboration for Revit (C4R) then you'll want to hold off installing the most recent update.
Autodesk have stated "We have identified a compatibility issue with the latest Revit 2016 UR4 update, which is causing degraded Sync with Central (SWC) reliability for those that installed it. We have confirmed this issue internally, and are working to resolve the issue within our services. Teams are advised to defer installing the latest Revit 2016 UR4 until we have resolved the matter on the Cloud Worksharing service. We apologize for the disruption this may be causing, and are urgently working to resolve the matter."
If you require any further assistance, do not hesitate to contact the Redstack Support team on 1300 667 263. Note support fees may apply for support if you are not a current client of Redstack. Learn more about our support options.