Separate declared and offered tracks
An MPD can contain several adaptation sets while the user interface shows only a subset. The dash.js documentation describes filtering based on codecs, required protection systems, essential properties and other requirements. That is specific documented player behaviour, not proof that every player uses identical filters.
Imagine a manifest declares two audio alternatives but the current player exposes one. The first question is whether the missing choice was absent from the manifest or removed during support evaluation. Those paths require different fixes and should not be collapsed into a generic language-setting complaint.
Selection preferences do not add support
A preferred language can guide initial track choice among available supported tracks. It does not install a missing decoder or authorise another protection system. Changing a language preference repeatedly cannot guarantee that a filtered configuration becomes usable.
For a developer report, retain the player version, declared track details and the reason for filtering if available. A menu screenshot alone cannot establish the original manifest inventory. Conversely, a manifest entry alone cannot prove a user could successfully select and hear that track in this environment.
Check the intended playback route
Use the service's supported player requirements and ordinary track controls. A comparison with another supported implementation can be useful if it uses the same media and account conditions. Retain any change in source or representation so a different result is not falsely attributed to a single preference.
This reference explains dash.js documentation and does not assert that IPTV Australia uses that player, exposes a particular language or tested the reader's hardware. The useful evidence chain is declaration, support evaluation, menu availability, selection, delivery and audible result. Each stage can add information without proving the entire chain by itself.
Questions about this guide
Does a missing menu item prove it was absent from the MPD?
No. A player can filter declared configurations.
Can language preference install codec support?
No. Preferences and technical support are different requirements.