Check which control started the session
An audio-output selector can send sound to a compatible speaker or receiver. An application’s video control and the system’s screen-mirroring control perform different tasks. Identify the actual control used before diagnosing the television as broken.
The saved AirPlay audio symbol in the asset collection should therefore be read as an audio marker, not a universal video-casting badge.
Verify the destination’s capability
Apple’s video/mirroring instructions require an appropriate destination and usually the same Wi-Fi network. A speaker appearing as an audio receiver is not evidence that it can display a video picture.
Use the actual television, Apple TV or Mac receiver supported by the desired task. If the display never appears as a suitable destination, investigate capability and local discovery before changing media credentials.
Check the application separately
Some applications offer their own supported AirPlay behaviour and content conditions. A video playing locally on the phone does not establish that the app permits that video to be sent through every output route.
Try the documented application method with an authorised source. If mirroring is used, remember that the phone’s interface can also appear on the display.
Make the symptom useful
Record sender, receiver, application and whether the action was audio output, video streaming or mirroring. That description distinguishes the missing picture from an account login or a simple muted television.