By my recollection this has gone on for years now.
Is the problem with LibreOffice? Yes.
Is the problem with gvfs? Yes.
Does the problem exist when you use another editor? No.
Will these two children ever work out their differences? Without adult supervision it doesn't seem likely.
I'm guessing most of you folks are mounting the share through Nautilus. That invokes gvfs and that's where the problem begins. Mount it the way your grand pappy mounted a remote share:
Create a mount point:
Make sure you have cifs installed:
Mount the remote share:
sudo apt-get install cifs-utils
Edit and try to save a document on the remote share.
sudo mount -t cifs //192.168.0.100/share-name /home/morbius/Netshare -o dir_mode=0777,file_mode=0666,nounix,nobrl