Applying stashes has started consistently failing with an error (see below). Viewing stashes doesn't work either, probably for the same underlying reason; when I select a stash the main pane goes blank with a progress indicator that never goes away.

The error sheet reads:

git -c diff.mnemonicprefix=false -c core.quotepath=false -c credential.helper=sourcetree stash pop stash@{0} 

One or more of this task's arguments is invalid. They cannot start with '-', and must follow git ref-format rules: https://www.kernel.org/pub/software/scm/git/docs/git-check-ref-format.html