Line in

Seems odd. Have you rebooted the speaker itself? Checked for and applied any updates?

If so, I would recommend that you submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it. Don’t post the resulting diagnostic number here, Sonos’ lawyers get sensitive about GDPR, I suspect.

There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.

When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

Do you have Autoplay enabled? Is there any kind of “time-out” that might come into play? 

Thanks for the responses. I forgot to mention that I do have auto play turned on. I tried it with and without “grouped devices” turned on. It seems to stay on the line in until I switch to streaming. Then when I try to go back to line in, it doesn't switch.  

I realized that it does switch correctly if I unplug and plug the 3.5mm side in and out. I was thinking that it would switch if it detected any signal, but maybe it only switches if it detects something being plugged in. I am currently using an A/B input switcher to two different sets of speakers, and I'm thinking that possibly the ground remains connected, so it doesn't detect that, either. 

Your auto play room should be the room where the Era 100 is located. You should also have the volume level set to about mid-way or slightly less to avoid blasting the speaker when the needle makes contact.

After streaming all you should do is select the line-in for your turntable (Era 100). You should not have to remove and re-insert the cable. Also before selecting line-in ungroup after streaming that may help so that the Era 100 is the only speaker. You can regroup after the record starts playing.