Keep the two video settings separate
Kodi’s Adjust display refresh rate asks compatible display hardware to change its output refresh rate. Sync playback to display instead changes playback speed to align video with the display. Similar names do not make them interchangeable settings, and their audio consequences differ.
Record both settings before making a comparison. Include the operating system, Kodi version and display connection. A receiver that previously identified an encoded track may show a different input after Kodi begins making the audio corrections needed by the playback-sync mode.
Compare a known supported audio track
Use the same authorised file, selected audio track and receiver input for both observations. With the prior configuration recorded, compare the supported output with Sync playback to display off. Kodi’s documentation identifies the interaction; the comparison establishes whether it explains this installation’s change.
Kodi also says Fixed output configuration disables passthrough. Its audio page separates the decoded-audio output device from the passthrough output device. Check the actual selected output and settings rather than assuming that enabling Allow Passthrough overrides every other processing choice.
Read the receiver result accurately
A multichannel PCM indication can mean Kodi decoded the audio before sending it to the receiver. It does not automatically mean all surround channels disappeared. Keep the receiver’s exact display and the audible result with your notes instead of reducing every change to sound being broken.
Enable only formats the actual receiving chain supports. For help, provide the file’s audio format, selected output, both video-sync settings and receiver indication before and after the comparison. This records the deliberate speed-correction tradeoff and separates it from a genuinely unsupported format or missing sound. A device-specific comparison is more useful than turning on every capability checkbox at once.