Just to check.  Are you looking at Settings>Manage>Voice Assistants>Amazon Alexa?  If it’s not shown as enabled, have you tried “Add to another product” on the same page?

Its all good in the Sonos app. This has to do with the Roam 2 not included in Amazons devicelist or something. Ive read about the same issues with other new Sonos products, move 2 as an example. Seemed to take months before it was resolved. 
 

Here is the differeance in groups with an older Sonos and the Roam 2.

Roam is in the living room under the name/group Stue. «soverom» has Sonos ones.

So the difference is that with Alexa enabled the speaker «knows» its location, so you dont have to specify which room you want to controll other devices in the same room as the speaker youre talking to. A minor inconvience for sure, but i would expect a brand new Sonos to be just as good as the old ones, or better. 

I am seeing the same issue and it does take away from the experience of controlling the Roam 2 along with the other speakers in my system.

Is this something that Sonos will fix?