Are you re-leveling the project schedule? I’m asking because you state that you have a series of not yet started tasks that are before the status date, meaning your schedule is showing not yet started work in the past. Typically, there are only a couple reasons that you would have un-started tasks in the past. 1) the tasks have mandatory constraints such start no later than and that date constraint is in the past. 2) you are leveling but you have the leveling option to honor task constraints turned on. This could allow tasks to be stuck in the past. 3) the schedule hasn’t been releveled and un-started work has therefore not been moved into the future (past the status date).
I can’t say for sure this will fix the issue, but this is where I’d start. Hope this helps.