Have seen a few stories about rebooking issues. Not sure I remember this one.
Girls fly to YYZ tomorrow. Used cancelled credits for bookings. When we did this they kept the original booking reference for one of the passengers, not the other which got a brand new unique one.
24 hours out, no invite to check in so we checked the AC site My Bookings and had to change my shorts after seeing this:

"The remaining value from your cancelled flight is ready to be transferred

You can now transfer the remaining value of all tickets and associated services into Aeroplan Miles or an Air Canada Travel Voucher."
All other usual icons like change flight or change seats are there but greyed out and dead.

Other booking ref. same thing. Pour through my emails to ensure I didn't miss a cancellation notice. NOTHING.

Dialing the customer support line with shaking hands and 5 mins on hold, agent says everything shows fine for both bookings, with a pleasant but kind of "Why are you getting yourself worked up over nothing?" tone.
Ummm because the website is basically telling me my flight is cancelled.
"Must be a computer glitch. You will have to check in at the airport."
So now my heart rate is halfway back to normal with this horrible foreboding that things won't go smoothly tomorrow morning.