I am also stuck in this "Synchornizing data" message. Ctrl-F5 a bunch of times causes the reload but no change in behavior.. This is on Chrome on Windows 7. Also failing in Safari on latest iOS. When I log in on firefox, there is no data present, but I do get a login to my account.
Everything was fine when I left my desk and went to bed at 3am last night.
Red Alert status. Killing me today on a key week in my business life.
Any help is appreciated.