The connection and receiving equipment can support different audio formats, so an output that works over one route may not work identically over another.
Why this happens
The sound path includes more than the player and the final speakers. A television passing audio through optical output, an HDMI connection through a receiver and a direct headphone output are different routes. Each has its own supported formats and settings. A device displaying a surround label does not mean every connection in that chain can carry the same signal. This becomes important when stereo plays normally but a particular multichannel source is silent or reduced to a different format.
Use the connection diagrams and format guidance for the actual equipment rather than choosing every surround checkbox in the player. Kodi’s audio documentation is useful for understanding why the chosen channel/output and passthrough capabilities must agree with the receiving system. Keep a working stereo comparison available and change only one supported output condition. If you move a cable as part of a test, record the old route so it can be restored. The aim is to identify the format the complete chain accepts, not to force a label the last device cannot reproduce.
A useful way to work through it
Write down the actual player-to-TV-to-audio connection route.
Compare supported stereo with the affected multichannel format.
Configure only capabilities documented for the receiver and connection in use.