Before going deeper into a yum rabbit hole, I forgot to ask you about the nmb service as well. Could you try to toggle the Samba service from the webUI and post the output from the commands below?
systemctl status nmb.service
journalctl -u nmb.service
systemctl status smb.service
journalctl -u smb.service
This was, for instance, helpful in another Samba troubleshooting linked below (and its link therein):
Also, could you describe what the UI shows? Did you indeed configure the Samba service by clicking on the little wrench icon next to “Samba” first? Do you see any error message or is the toggle automatically reverting back to OFF after a few seconds?
Hope this helps,