Actually, when I called IRCC last month, they advised that I do an upfront medicals. After doing the medicals, I called again to ask how to upload, and the agent (a different agent from the first one) said that there was a note on my file stating 'advised to do upfront medicals'. After uploading the medical document, they emailed me saying "We acknowledge receipt of the documents and wish to inform you that they have been added to the file. Please note, for technical reasons,
they may not be visible in your online account. Rest assured that your supporting documents are indeed added and available for officer review.". So I think I am pretty good on that end.