Maybe an iOS device, that is compatible? 

Every other 20 speakers have no problem with true play 

Then there’s likely something odd going on, unfortunately you hadn’t included much information in your post. 

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

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.

​@Jay A 288 

A couple of questions….

Are the Arc and Era 300’s Bonded (setup) as a home theater or do the Arc and Era 300’s just happen to be sin the same room. If the latter then they will not TruePlay as a unit.

Also what is meant by the following statement…

• “Every other 20 speakers have no problem with true play’

Yes they are bonded okay thanks for the info 

I have 20 other speakers and have no issues with true play list 

I am told that Trueplay is only available on the IOS App..is that correct..I cannot find it on the Android App similar to this report.

That’s correct. Some units support additional methods, not requiring an iOS device.

Does Sonos suggest how to set up the systems without an Apple phone. My main home cinemas comes with a microphone to put in the middle of the room.

You can set up a system using Android. There’s just no advanced Trueplay for Android. You could use a borrowed iPhone for Trueplay.