You may have an issue where you Sim appears to always be busy or stuck without any briefcase or whistle icons. You may be unable to send them to work or call them because these icons are not available. It will look like the Sim's task bar is constantly empty, though they may not be performing any task.
To resolve this issue, send your Sim to work via the "Occupations" tab in the bottom right hand corner of the screen. Click the brief case icon on the right of their name. When the shift is complete the issue should be resolved.
What does it look like?
If this did not resolve your issue, please contact Support.