addpath using sftp on linux

I run a script on

/run/user/1000/gvfs/sftp:host=dal.imws.tuwien.ac.at,user=jkalliau/srv/share/public/somefoldername/

and want to use addpath('./subfolder')

Everything works. If I run path I get:

    MATLABPATH

  /run/user/1000/gvfs/sftp:host=dal.imws.tuwien.ac.at,user=jkalliau/srv/share/public/somefoldername/subfolder
  /home/jkalliau/Documents/MATLAB
  /opt/MATLAB/R2016b/toolbox/matlab/datatypes
  /opt/MATLAB/R2016b/toolbox/matlab/elmat
  /opt/MATLAB/R2016b/toolbox/matlab/elfun
  /opt/MATLAB/R2016b/toolbox/matlab/matfun
        ...

If I run the script; addpath('./subfolder') again I get following warning:

Warning: Name is nonexistent or not a directory: /run/user/1000/gvfs/sftp 
> In path (line 109)
  In addpath (line 88) 
Warning: Name is nonexistent or not a directory: host=dal.imws.tuwien.ac.at,user=jkalliau/srv/share/public/somefoldername/subfolder 
> In path (line 109)
  In addpath (line 88)

The next time (every second run) addpath('./subfolder') works again.