So I didn’t actually face this problem for almost a year even though the change had happened before then and the reason was my container for Sonos SMB library share wasn’t rebooted in that entire time and only did when a long enough power outage recently forced shutdown of my container host as the UPS reached its designated drain %.
In any case, after four years from the previous post, you will need to add this line in your /etc/samba/smb.conf to allow Sonos (S1) access to your Music Library: unix extensions = no
PS: While Sonos has had a lot of blowback from their app issues, their approach to supporting 14 year old devices (in my case) is commendable. They have a frozen in time app called Sonos S1 and it gets no new features or upgrades, but continues to work. Contrast this with Google that just basically neutered the entire purpose for which people had bought Nest Gen 1 and Gen 2 Thermostats – and please, give it a rest with how long should a product be supported. That sound idiotic when the product lifetime is clearly measured in decades – if you didn’t care to support it that long, just stop entering the product category altogether with your tech-bro shit.