In the Scene Outliner, Visibility ( eye icon ) can only be set one actor at a time.
Select more than on actor, and click the eye icon. The expectation is that the eye will toggle on all selected actors, but it only toggles on the one you clicked on.
Thank you for your report, I’ve submitted an issue for this in our database for tracking. For now, the workaround would be when you have multiple actors selected to press H to hide all selected and Control+H to un-hide all selected.
Please continue to report issues like this in the future!