18 months in, and yeah, this tracks with what a lot of people are dealing with right now, IRCC's backlog is sitting at over 700,000 PR applications as of mid-2026, so long waits unfortunately aren't unusual.
On the ATIP/GCMS notes specifically: three months without a response is frustrating but not abnormal. IRCC doesn't process requests first-in-first-out, and when there's a systemic backlog, delays tend to stack in roughly 30-40 day chunks rather than resolving on any predictable schedule. Worth knowing too, IRCC officially stopped responding to status inquiries about ATIP requests a while back, so following up repeatedly won't speed anything up, it just adds noise to their queue.
As for calling IRCC directly, most people find it's not very useful beyond a basic gut-check. Phone agents typically only see what you already see in your online account, they can't access GCMS notes or give you specifics an officer wrote, and disputes/complex cases especially tend to just get a generic "we're processing it" response.
Given you're at 18 months, it might be worth checking IRCC's posted processing time for your specific application stream, if you're sitting well past that, the official next step is submitting an inquiry through IRCC's web form, that's the formal channel for flagging a stalled file. And if it drags on much longer past the posted time with zero movement, mandamus applications (a federal court order compelling IRCC to make a decision) have actually succeeded specifically in cases where Express Entry files sat 18+ months past the posted processing time, so that's a real option down the line if it comes to that, though obviously most people don't need to go that far.