You can fix this by doing the following
Click the "settings" cog --> "App settings" --> "Synchronization"
Then in the section "Synchronization settings"
Click on the "Server" URL --> Copy all the URL so it is saved in memory --> Remove all characters from the end of the line up to the "M" in .com
Then press save
After, click again on the "Server URL" and paste back the URL you previously copied to memory.
Press save, the APP should now be OK.
This happened to me two times so far, the first time I uninstalled and re-installed, but that aint no solution. After some digging I came up with the above fix.
No idea why this is occuring ......