Whenever they send a request, there's a line in ECAS that: We sent you correspondence on <XXX Date>.....
You mentioned that you received one request on Oct 19th, 2020. Do you see any line in ECAS for October 19th? Because its possible that they posted an update on ECAS little late i.e. on Oct 28, 2020 for the request which was sent out earlier on Oct 19, 2020. Its very unlikely though.
For Oct 28, 2020 correspondence request, if you don't receive anything by Monday you should raise a Case Specific Enquiry. Also, make sure to check all the associated email-ids (sponsor, applicant, representative) for IRCC requests/letters.
I will share my own experience related to email-ids. At the time of application, I entered one email-id for the sponsor and a different email-id for the applicant.
We only used the sponsor email-id for myCIC registration, for raising Case Specific Enquiries or emails to IRCC-Parents-CIC. There was zero communication on the email-id used for applicant, but guess what the golden CoPR email actually came on it.
We hardly used to check that email-id because all the requests/notifications from IRCC used to come only sponsor's email-id. Somehow we randomly checked the other id on the day we got the CoPR email and got the much needed document.