Sync halts on MacBook Pro after sleep in Desktop Posted January 20, 2017 · Edited January 20, 2017 by tranquilo · Report reply It's not that the sync is failing; the entire sync mechanism in the app itself ceases to function. The sync icon turns red and going into the sync settings and clicking on "Sync now" just greys out the button. Nothing actually happens. I'm using the WebDAV method to FastMail. But again the sync isn't failing, it's not even trying. Once the app is quit and re-launched everything works again as it should (until the MacBook sleeps again).