If there are no assessment notes in the gcms notes then its the old eligibility. See if the assessment and pre-assessment notes have changed from the previous.
A background check does not necessarily mean a security check, it may also mean verifying your updated information like the deferred LOA. Your university previously took several months to verify to IRCC, UoC, right? so the hurdles if from them.
There is a 4-digit number just before my application number, on the left of the left of application number starting with an S. Can someone tell me what this means?
If you tell IRCC in response to their email that you did have refusal then that would be considered a confession and that you did not challenge them. Best approach is to get a lawyer because if banned, you will face issues with visa for other countries too.
You are not aware of any refusals? how is that possible? even if your applied for you, they would have told you if it was refused. Usually they don't go beyond the search on the five eyes countries, so you should know if you were refused by US, Canada, UK, Australia or New Zealand.