You are in the same boat as many people. It appears, from this forum, that although security could be 'complete,' the box or field in your account may not get 'ticked' by the right officer until the day you get your eCOPR. It's not a very transparent process and security is only one of many steps in Background Check so it can seem to take forever.
Ordering GCMS notes (through ATIP from IRCC or CBSA) will not reveal much about why security is being held up because (for broader national security reasons), security notes are generally not provided (they are redacted). The most you will generally find out is:
2. Security
Before foreign nationals who apply for a visa, permanent residency or file any other immigration application can be admitted into Canada, it has to be ensured that they would not present a risk to the safety or security of Canadians. All foreign nationals undergo a security screening, which is done primarily by partner agencies, such as CBSA and CSIS. You can read an in-depth article on security screening here. GCMS notes released by IRCC will redact the security-related information in the GCMS notes pursuant to section 15 / 16 of the Access to Information Act. If the security screening has not yet started the security field will reflect “not started” against it. However, if it is in progress or passed, it may show as blank and have s15/16 listed on the top right corner of the page.
You may want to order GCMS notes for other reasons, but they won't reveal details about 'security' issues. Best wishes!