Been reading the posts here recently. Looks like a few of us are stuck in the PM03 Grant Review Ready. I did a few more steps to try and understand what might be happening here. Usually, IRCC will not send applications to PM03 level, unless some additional checks are required. This is outside of CBSA and CBPS. This usually involves the CSIS, where the moment it hits CSIS, the apps are declared as non-routine.
This is what I found out after I had my MP reach out to the IRCC. They mentioned that my app was non-routine due to some security related components that needed to be cleared out.
CSIS is currently extremely backlogged, and unfortunately, IRCC will not make a decision unless CSIS comes back with a response to them (there is no obligation of a lead time).
So I would say, that if you're sure there's nothing flagging your app (that may be a security threat to Canada), patience will be your true friend. Sorry I couldn't be of more help. Stuck in the same boat.
I have requested my notes from CSIS, and will let you know how things go.