I’m not an Android user, but that suggests to me a version mismatch between your controller and your speakers. Have you checked for updates to both of them?

Alternately, have you called 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.

Just checked on my Android Pixel 9a. The add ML add shared folder button is active, not grayed out.

All the more reason to call Sonos Support directly to discuss it. They can take the hard data you provide, assign it to a ‘bug’, and provide it to the coders. Something that doesn’t occur here in these community forums. 

I make it without any error on my Samsung but you may need call the Sonos Support