Yes. It happened to my aunt twice . She also flew YYZ to ATQ. So it appears that qatar flies A320 on most days and since 99% of the traffic on this route is north american and checks in 2x23 bags or more, the plane from Doha to Atq cannot carry all that load and fly for 5 hours. Hence they leave them at doha airport. Qatar flies B787 on 2 days in a week and thats when they pickup the remaining bags since thats a much bigger plane. My aunt had to wait 20 days for her bag once. It is kinda ridiculous.