CentOS - Jul 2018 - FF60 does not allow download to ssh/davs

Hello All, 

this concerns fully updated Centos7 / Mate machines; 
I have people connect to ssh en davs locations. In /home/user/.gtk-bookmarks I
put entries like
ssh://192.168.1.8/data data-remote 

People can then click on the bookmark in the file manager and connect to it. 

Since FF60 people can no longer save files for instance from their mailbox to
these "mounted" locations. Before, when choosing "save as",
the mounted ssh location would
appear in the download window. 

I guess this is not a bug but something one can disable/enable in about:config. 

Many thanks for any advise on this. 

greetings, J.