Since the latest release the surround files on ISO-SACD’s are no longer detected and do not show up as multi-channel in the library… (MacOS)
This is fixed in 3.5.19
You’ll need to get the SACD ISO reread to have the displayed updated.
If you don’t have them in a manual playlist, the easiest way to do this is to remove the synched folder that contains them, then add it again.
Or if you know how to use the command line in Terminal, you can use the “touch” command.