Hello,
I'm kinda confused by this whole thing too. My partner was sent an email (the last correspondence about our app) from the VO in Mexico saying that they acknowledged receipt of our email with the attachments of Schedule A background declaration and Supplement 1 to background declaration, as they requested. This email they sent on March 23 said:
... please be advised that your file is in transit and has not been yet received by our Visa Office in Mexico City.
All communication (unless otherwise specified) will be sent to you by email. Our office will contact you when we receive your file, and we are ready to proceed to the next stage of processing. An exact schedule of when this will be done is not yet available.
As your case is in transit, this office kindly requests you to be patient. No further action is required of you at this time; nevertheless please monitor your email closely as you may be contacted by someone for additional information.
I was not expecting them to send us anything to acknowledge receipt of our email, but it was nice to hear something from them, even if it says our file was in transit. Should I be worried about that because IRCC sent us an email on March 13 (10 days before that email sent on March 23) saying our file had been transferred to Mexico? I have visions of our app in some warehouse waiting to be shipped or worse case scenario it's lost in the abyss somewhere between Canada and Mexico City.
My guess is that the next email that will come (hopefully) will be AOR2 when they actually open our file in Mexico. We'll see if that happens in the next few weeks as some people think it will.
With eCAS, nothing has changed since March 2 when they requested Schedule A and supporting docs to be sent/uploaded. My third line still indicates that they sent us a request to send/upload documents and to do so by the requested date, etc.
Our GCkey (myCIC) account status has not changed at all since beginning of March either.
I don't know about sponsor application status, but I thought eCAS shows only the PR app status. Our GCKey account didn't mention anything about sponsor app status either. I (the sponsor) received an email saying my sponsor app was approved and that was the only mention of SA I got.