Also a December 27th applicant, I just got off the phone with IRCC when I was told my application was sent back. It hasn't come to our mailbox yet, but there can only be two possible reasons this happened.
1. Some of my forms were outdated, since they updated them a month before I sent them in and I didn't check. Big mistake on my part.
2. I've been reading some people's forms being sent back because of the form IMM 5669. The forms asks you for an electronic signature but apparently they want a handwritten signature too. I don't know if this has changed since the time of the posts I read.
A real bummer. I really needed to start working soon. This is going to be hard.
A question about implied status. Luckily I applied for a visitor status extension last month. Haven't heard anything back, but my original status expires today. I know I have implied status until I hear back from that, but will I have to let IRCC know that when I resend? Will they have record of me applying to extend? Would I be considered out of status when I reapply? Or does the implied status save me from having to do anything special?