I doubt there is a bug but it could happen at this late in the game, but you also do not provide what version of software you are running so kind of difficult to say there are any issues.
What day do you have the Long SMART tests scheduled to run? The day after is when you should check it to see if it runs. Also, since you didn't post a screen capture of your settings (what you want and actually configure can easily be wrong, been there myself), just so you know you cannot run a SMART Test when one is already running. For example, if you start a SMART Short test at 00:00 every day and then schedule a SMART Long for 00:00 or 00:01 on any specific day, the long test will not run. I'd say 99% of SMART Short tests are completed within 2 minutes, unless they run into read failure. I like to run a SMART Short test at a given time every day of the week and then a SMART Long test no sooner than 5 minutes later once a week.