The line-in option is not showing up on the Sonos app.
Best answer by pwt
I’m having the same issue. Line in disappeared. Rebooted then it appeared, however has gone again this morning. Software issue. Must be.
Also, do check the Line-In cable and the connections. Note that the Line-In option will only appear if there’s a cable attached to the Line-In inputs. A defective cable could cause the Line-In option to appear/disappear. I’d try a different cable as an experiment.