Has an application thats been processing ever been sent back?

Hey so-I wanted to ask causw nervous energy but my application no longer is appearing in IRCC tracker and yes I did all the tricks and typed things manually and what not to see and still nothing. I assume it’s just a technical error especially considering my application has been processing since 10/28 and I can’t think of a reason why it would be sent back.

But my main question is has anyone had their applications sent back before even when it was put in the processing stage? If so, why?