When I last looked, inverted Eras were not supported in Trueplay. Are you using Trueplay? 

@APoort 

Dolby Atmos/Spacial uses upfiring speakers, not downfiring!

But Sonos does recommend inverting them if they’re being mounted too close to the ceiling. 

Interesting. 
In my Googling, I just found this is indeed the case. Always happy to learn! I can’t fathom how Atmos would work like that but hey, not my speakers! But also saw this from a year ago which stated Sonos had yet to support inverting but was meant to soon, according to Corry’s post. Is it still not supported…?

Most AVR set ups with Atmos speakers set into the ceiling fire downwards? Pretty easy to fathom imo. 
It’s about time Sonos sorted this problem, but the app is still in a state so I guess they’ll be concentrating on that. 

i have the same issue, in contact with support trying to solve it.

seems to be a new feature/bug since few days

New feature, I think, that they’re notifying you. It was always noted in the setup guide that Trueplay for inverted Eras was planned as a future feature. 

Hi @APoort et al

Welcome to the Sonos Community!

We are aware of an issue whereby “Era 300 is in an unsupported orientation” is erroneously reported in the Sonos app. While TruePlay Tuning of inverted Era 300s is not yet supported, the inverted speaker orientation is. We ask that you just ignore the error message that you are seeing until this is resolved in future update. 

I hope this helps.

What is the ETA on trueplay for the inverted speakers?  It has been coming soon since they were released. 

Hi @StreetTuff 

Good question! Although it does not sound much different from what was already said, I understand that TruePlay support for inverted Era 300s is coming soon, but I cannot give you a date - other issues currently have priority for our development teams, as I’m sure you’ll understand. Please be assured that we have not forgotten about it.

I hope this helps.

I see there are some updates to trueplay...does this include support for inverted Era’s?   

Hi @StreetTuff 

Not as far as I am aware, but due to the following post on another thread, I am currently seeking confirmation:

At present, it doesn’t look like support has yet been added, but I will come back with confirmation once I have it.

Hi @APoort et al

I am happy to confirm that TruePlay Tuning now supports the use of inverted Era 300s in a Home Theatre setup.

I hope this helps.