OK, I had to come back to give everyone the solution that to the problem I created for myself. It turns out a couple of months ago I had a rogue app that was consuming data in the background.
I uninstalled that app but where I went wrong was under Settings>Data Usage> I Restricted Google Services,checked Restrict Background Data. Un-checking that and restarting my phone and Android Device manage has worked perfectly since. It now seems obvious that thus was the problem but maybe it will help someone else sometime. Cheers!