Sorry, but what goes dim?

Do you notice the plugin notification icon on the left end of the address bar at that time? That is where you could grant the site permission to use Flash if it uses Flash. Example screenshot attached (from an Adobe test site, not sure which iHeartRadio page you're on).

If you use extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) that can block (wanted) content (e.g. Adblock Plus, NoScript, Ghostery, uBlock Origin) always make sure such extensions do not block (wanted) content.

• make sure your extensions and filters are updated to the latest version