I just updated to Sourcetree version 3.3.6 and the automatic refresh of files no longer works. I have to press F5 for Sourcetree to update. Prior to the update, I did not have to do this. I checked the settings and automatic refresh is checked. I unchecked it, saved that changed and then checked it again but that didn't resolve the problem.
Note: The "Affects Version/s" option does not show version 3.3.6 as an option to select so I just selected the highest version.