Dashboard filters are locked in Shared Widgets
As an enhanced security measure, when you share a dashboard as a widget, run-time filters are now locked.
The Revert button is fully functional. As a reminder, when viewing a Dashboard, you can revert changes you made to run-time filters using the Revert option.
Note that filters are reverted to the last saved state in view mode, and not necessarily to the last saved state in edit mode.