October 2016
I've played the Police Station and Movie Studio long enough that the first few sims to work these professions have advanced to old age. When the first two left the police profession, the NPC's they'd been helping vanished, and the younger sims had new NPC's to help. This time, they're stuck. At one point my Police Station had 4 NPC's who the two current police officers weren't able to assist because they had tasks that were either in the wrong specialization or too advanced. Two of those disappeared, but two are still stuck. My Movie Studio has almost the same problem. There's a VIP NPC who has two tasks for my Director, but she can't do them because they're for higher levels. She needs to help one more VIP NPC to advance to the next level, but can't because she can't do those tasks. Is there any way to get these NPC's to clear? It's making these two professions virtually unplayable.
October 2016
If your sims can't help the NPCs because they haven't built the needed workstation but they are at the level for the workstation, then there isn't much you can do except keep helping the NPCs you can until you get enough resources to build. If you sims can't help the NPCs because they're not at a level that they can even build the workstation needed, then that needs to be reported to support.
Go to this link to get to the support form. http://answers.ea.com/t5/The-Sims-FreePlay/INFORMATION-The-Sims-FreePlay-Support/td-p/1877383