Keep the successful stage
If the intended receiver appears and can be selected, preserve that observation. It is evidence about discovery in that app and network context. It does not prove that every selected programme can be played, that the account permits the requested route or that all media formats are supported.
A report that only says casting does not work throws away the distinction. Write whether the receiver is absent, selection fails, a loading screen appears or playback begins and then stops. Also note whether the sender continues to play normally.
Confirm the actual endpoints
Use a compatible Cast application and receiver, with the relevant network conditions in Google’s instructions. Read the app publisher’s supported route for the media. A generic browser page, local file and protected subscription stream should not be assumed to have identical casting behavior.
Keep one item selected while investigating. If an authorized comparison item plays, retain its identity and the difference. That can narrow the question without turning the working item into a guarantee about the whole catalogue. Avoid changing the app, receiver and programme simultaneously.
Ask the playback question directly
Include the application and version, sender device, receiver model, selected media and the exact visible result. Account information can be provided through the appropriate private support route when needed; a public screenshot should not expose a full access URL or token.
If the app publisher says the requested media does not support that route, use its supported playback option. Do not treat receiver discovery as a reason to promise that mirroring, another browser extension or an unrelated player will automatically remove the limitation.
Questions answered
Does receiver discovery prove media compatibility?
No. Discovery and playback are separate stages.
What comparison is useful after discovery succeeds?
Keep the same application and endpoints, then record what happens with the actual item and one relevant authorized comparison.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.