SourceTree hangs on SSH connections after a couple of time

After a couple of time (more than 60 minutes) each try to do a SSH connection by a button or command, like Pull or Push fails. Sourcetree sems to hang until we abort manual (see scrennshot, this message keeps open for a long time).

Opening a bash shell and manual executing the commands show under "display all" are working.

After closing and restart Sourcetree it's again working for some time.