If anyone else is frustrated and thinks it is confusing the new way Canvas is using the eye icons to show muted/unmuted grades by using the same icon for two totally different statuses (grayed out eyeball for both ungraded and hidden and also for graded and posted)? Can you please complain about it and hopefully we can get Canvas to change it.
You can vote it up here @ https://community.canvaslms.com/ideas/14598-visibility-icons
Thanks for your feedback! Our product manager is aware of that idea and is reviewing options to see how we can improve the experience in the New Gradebook.
In the meantime, we've created a comparison resource that may help you with training. It also includes videos on how the existing functionality works: New Gradebook and SpeedGrader Muting Behavior Changes.