This is what I have seen here so far and CIC is unpredictable so far. We never know what might they come-up with. They have cancelled the applications like anything during end of april and 1st week of may. But they reopened once the applicants contacted CIC with the missing documents.
BTW, what is your ECAS status, If it is In Process from App Received, then you may expect any document request (like SCH-A, NOA, New Employment letter if you're close to end of your current Closed WP etc) or RPRF fee request if you have not paid during the eAPR submission or finally PPR.
Good Luck!!