The background check is usually completed before the eligibility but only shows 'completed' when an officer re-verify all admissibility sections and infuses the outcome into GCMS.
PPL seeing 'in progress' these days are generally under security screening which may take a longer(unpredictable) period to reach a final report for IRCC to determine a final decision.
Normally when ppl received a pre-arrival letter means they are just waiting for the last manual steps performed by an officer; Or, waiting in queue to be automatically updated and CoPR generated.
Some are lucky enough to see all "completed" within a few days, especially background verification checks completed which are followed by CoPR and PPR.
Since this "final decision" is a manually operated function, some, like me and others in this thread, are experiencing unforeseeable delays.
Luck, again, is all we need at this time.
