Very similar situation but i got the invite December 2020, in which I could not go due to the pandemic. My application changes to approved in June 2021 and i spoke to IRCC in which an agent told me my medical was sent for an extension in October 2021! Did you try calling them? I will be trying to call again this week..My COPR expired on Dec 2020 and had not heard anything form IRCC until March 2022 got a pre-arrival letter. And nothing ever since.