Backslash in the title (in 7.1 SP2 only in the end of the title) will cause the Smart Tasks to not work - you can click but nothing will happen. As Joshua said, manually removing the backslash from the task name in database works. Also, TECH154186. When this is happening, you will have the task entry in Incident History (green entry) and you will have Smart Tasks. SD up to and including 7.1 SP1 is affected, SD 7.1 SP2 only has this if backslash is in the end of the title.
Special characters and long incident titles, check: TECH133480, TECH133412. As far as I know, these are fixed in 7.1 SP2. When this is happening, you will have no task entry in Incident History and no smart tasks. SD up to and including 7.1 SP1 is affected, SD 7.1 SP2 is not.
If the entire right pane is not visible, but there is a task entry in Incident History, you are possibly seeing the problem with HTML (namely <style> tags) in the Description, issue in this KB article: TECH183216. All current SD versions (up to and including 7.1 SP2) are affected.