Just an update. I tried it on a new wireless charger as assumed this was the issue. But same result. Sonos roam powers off on wireless charging. But is fine when direct charger attached

You’re sure it isn’t entering sleep mode?

https://support.sonos.com/en-us/article/put-roam-products-into-sleep-mode

I’d be tempted to remove it from the charger, then power cycle it using the buttons, before placing it back on the charger ‘base’, just in case there is some electronic ‘glitch’ that could be cleared by reloading the OS. 

I'll try that thanks 

I did factory reset it and the same issue. 

Worried the speakers got an issue. 

I'll update once I try your suggested steps 

Hmm. I’d think a factory reset, while not normally a good ‘fix’ for anything, would have fixed the reload of the OS, so that makes that part moot. 

Since there was a firmware (and Android controller) update this morning, I’d at least install them, and test. If it continues this behavior, I would call Sonos Support directly to discuss it.

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