I suggest you contact your local Member of Parliament (whom you can locate with your postal code at www.ourcommons.ca). Their office will then contact IRCC on your behalf to clarify the reason behind the AOR delay.
I already use the Check Application Status (CAS) tool. Do I still need to create a GCKey account to track my application?
What is the difference between them?
It is case to case basis, I already had given medical during my TRV application in 2021, so they did not asked for new one for me. You will receive medical request soon hopefully if not already received it.