sshfs crashes when doing cp or tar on a directory

I'm using sshfs over a vpn connection (Cisco anyconnect, openconnect).

When doing either 'cp -r' or 'tar' on a directory, i.e. reading and writing on the sshfs-mounted filesystem, the command fails and sshfs freezes. (Copying from the sshfs-filesystem to the local filesystem works ok.)

The command cannot be stopped using ctrl+c.

In the case of cp: Of 10 files, only the first one is written.

The terminal (gnome-terminal) crashes and needs to be forcefully killed.

The terminal also crashes when cd-ing to the mountpoint.

This situation can be resolved by killing ssh.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: sshfs 2.3-1
ProcVersionSignature: Ubuntu 3.2.0-32.51-generic-pae 3.2.30
Uname: Linux 3.2.0-32-generic-pae i686
ApportVersion: 2.0.1-0ubuntu14
Architecture: i386
Date: Fri Nov 2 09:21:07 2012
InstallationMedia: Ubuntu 12.04.1 LTS "Precise Pangolin" - Release i386 (20120817.3)
ProcEnviron:
 LANGUAGE=de_CH:de
 TERM=xterm
 PATH=(custom, user)
 LANG=de_CH.UTF-8
 SHELL=/bin/bash
SourcePackage: sshfs-fuse
UpgradeStatus: No upgrade log present (probably fresh install)