The soundbar connection or selected output format may not support the same audio path as the TV speakers.
Why this happens
A television can play a source through its own speakers and still fail to pass that sound to another device. The selected output, connected port, audio format and capabilities of the soundbar all matter. The stream itself has already some usable audio when the built-in speakers work, so changing the service login is unlikely to explain the difference. The next comparison should follow the signal from player to television to the external audio equipment.
Keep the same source playing and inspect the soundbar’s selected input alongside the television’s sound-output choice. A supported stereo output can be a useful diagnostic comparison when an automatic surround format is silent, but the right setting depends on the equipment. Apple TV’s audio guidance, for example, provides a manual format route for systems that cannot use the automatically selected format. Use the equivalent manufacturer instructions for your own setup. Restore a working setting after the comparison and avoid unplugging or reconfiguring several parts of the chain at once.
A useful way to work through it
Verify the TV output and the soundbar input refer to the actual connected route.
Compare a supported stereo output with the silent automatic/surround setting.
Keep the source and player unchanged while testing the external audio chain.