We applied 4 June 2018 (full timeline in signature). After IRCC cancelled an interview in July, we were again summoned to attend a relationship interview on 13 Sept 2019. The interview went smoothly, although we were there for almost 4 hours. At the end, the officer suggested that there were no issues, but of course we have to wait for a formal letter.
I asked about the status of the other parts of the process (since as far as our GCMS notes indicated, nothing has started). The officer indicated that they no longer do any of the other processing if there is any reason to suspect the relationship. So, now, after almost 15 months, they will *start* the background and security checks. She seemed to hint that we might have to re-do some of the security documentation.
As an aside, after receiving an essentially empty GCMS report in July (ordered on the 1 year anniversary of the application), we ordered a second report on July 16, but have not received a response after two months. Based on my conversation with the agent, there doesn't seem to be much point in pressing for it.
If any of the "seniors" are reading this, it no longer seems like "order your GCMS notes" is useful advice for people receiving interview requests. If what has happened in our case is typical, the file will contain no information, if you even get a response.