My ~/.ssh/config file uses the following parameters for persistent connections:

ControlMaster auto
ControlPath /tmp/ssh_mux_%h_%p_%r
ControlPersist 2h

However, when I try and perform any operation that happens after a connection has expired (e.g. after my mac has been sleeping for 20mins+), it crashes SourceTree and requires a Force Quit to get it working again. After that it works fine.

Persistent connections are something of a must for us as we run our stash on AWS and it can take a while to initiate a connection.

(This bug has been affecting me for ages - about two years - but it has taken me this long to narrow down the cause to the ssh configuration)