Odd one.
I did some WSE2012R2 Maintenance (Oct rollup patches) and added a new drive to the pool. I noticed that the Users and Devices in the WSE Dashboad were blank when run on the server I I could not Sign In from a PC at all. On checking, the WSE Mgt Services was not running. I could start it but it would stop again.
Tried the C:\ProgramData\Microsoft\Windows Server\Data\DevicesInfo.bak --> C:\ProgramData\Microsoft\Windows Server\Data\DevicesInfo.xml but that did not work. In the end I had to do a "run wbadmin delete catalog" and then resetup the Server Backup from the Dashboard.
Seems OK again.
Thanks
Nathan