I don't have any particular insights on what the inside thinking might be. I would only be doing informed speculation.
To be fair, the original proposal from India and South Africa was flawed. One could make the case that it was self-serving, that it would have benefited firms in India and South Africa, so there were some issues to be sorted out.
I suspect we are waiting because the issue might simply go away, or there might be important players who come onside, such as the Biden administration, which actually matters for Canadian foreign policy. There's prudence involved, which involves political risk as well as the technical nuances of the proposal.