After staging the files, when 'Commit' is clicked, the progress bar shows as thought the files are getting committed.
Then, this popup shows up, saying 'SourceTree has stopped working'.

The issue is noticed in 'Commit' (with & without the 'Push' ticked).

On closing and re-opening the source, we can see that the files are committed & ready for push (or already pushed, if the checkbox is ticked).