Created an ODS file in libreoffice calc on windows and set it to "shared mode" and saved on a smb share. When opening that file on another windows machine from the smb share it correctly informs me that this is a shared file and opens in shared mode. When opening that same file on the smb share in linux (ubuntu 15.10) libreoffice calc does NOT inform me that this is a shared document and instead opens the document in read-only mode. Clicking "edit document" allows me to edit anything despite it being a shared document. This means that if you are on linux, "Shared mode" only works if you are not sharing the file... This seems similar to Bug 90552.
Indeed, it must be the same feature, closing this request as duplicate. *** This bug has been marked as a duplicate of bug 90552 ***