Thank you for confirming the version.
Can you continue to keep me posted and inform me if this happens again? I would recommend making notes of any system changes or updates on your Displays in case this helps to explain the issue.
Also, if it should happen again, can you check the following locations:
C:\users\<The User with Xibo player installed>\Appdata\Roaming\- There should be an XML file at this location named
XiboClient. If you open it with a text editor, does it contain the correct CMS information?
Also check your Xibo Library folder and look for a file named
hardwarekey. If you open it with a text editor, does it contain the hardware key for the Player?