In activity feed or media tab, when I click to open an image, the lightbox opens a WP page saying: "nothing found, try to search with a different tag". Anyones know what's happening?
You can first try testing your website by activating any default theme of WordPress and also disabling all other plugins. This will define if there is any conflict with either a theme or any plugin.
If the issue still persists then kindly provide the debug info log on your website. You can find it under rtMedia Settings -> Supports tab.
Settings -> Supports