I suspect the overall_share file got truncated, try ls -l /etc/samba/overall_share
the mycloud and windows shares are controled differently, below is what I found and posted a few days ago. If you try the system only restore please let us now the results. also any steps leading up to the issue.
this happened to me today, a few days ago I upgraded to the latest FW (v04.01.01-413). when I created a share today everything was fine while the share was public. when I set permissions on the new share I lost all SMB shares. the /etc/samba/overall_share file got truncated, I manually re-created it, I suspect a system only restore would re-create it too.
I tried to create and set permissions on another share to re-produce the issue but it is working fine now.
until there is a resolution I would suggest anyone with any Linux experience to make a backup copy of the overall_share file before adding or altering any shares