As of Mosaic 2.7.X we have received reports of controllers appearing in a locked state despite no password being set on the controller.
A locked controller will appear in the Network tab of Mosaic Designer in the following manner.
When attempting to interact with a locked controller, a user will see the following prompt
To resolve this issue, save your configuration and close Mosaic Designer.
Re-open the program as an administrator. The controller should now appear unlocked (an open golden padlock) in the Network tab.
We are working to resolve this issue and plan to have fix in the next release of Mosaic Designer.