I am one of the applicants with a PA from Ukraine, and also have the benefit of being able to speak with IRCC on the phone regularly through the diplomatic assistance line (no, I am not a diplomat. The Ukraine hotline happens to be the diplomatic assistance line).
They have said to me many times that the updates you see in the top right when you login through the GCKey mean the agent is working on the file. At times the status of individual line items in your status may not be updated right away (ie medical passed), but it is noted in the system on there side. They said that there are many fields in the immigration system we are not able to see in the tracker or GCKey data, and do not always show on the GSM Notes, but when the agents enter information, it triggers a change to the "update" date.
They have said a few times that the multi-part security checks include other country information sharing check, border security check, and CSIS security check, and is not to be mixed up with the background check which is the police check process. The CSIS security check is the part that immigration agents know the least about since it involved the Canadian Intelligence (ie spy) Agency, and it takes the most time. For some people it is a quick process, and for others depending on background and country of origin it can be a long process. They said that the part that results in the most "ghost" updates is the security check, which is also the last process before PPR. The security check starts as soon as the PA and dependents receive a "medical pass". Here is an example of my PA's ghost activity after the medical pass and during the security check process:
Outland Online Submit: 12 Jan 2022
TRV and Work Visa and arrived in Canada under Emergency visa: 13 May 2022
VO: London, UK
Pass Medical: 23 Jul 2022
Ghost Update: 2 Aug 2022
Letter Request (Un-accompanying Dependent Schedule A - security check information): 4 Aug 2022
Ghost Update: 5 Aug 2022
Uploaded Schedule A: 7 Aug 2022
Ghost Update: 8 Aug 2022
Ghost Update: 15 Aug 2022
Ghost Update: 16 Aug 2022
Ghost Update: 18 Aug 2022
Ghost Update: 19 Aug 2022
Ghost Update: 25 Aug 2022
Ghost Update: 30 Aug 2022
Ghost Update: 31 Aug 2022
Ghost Update: 1 Sept 2022
Ghost Update: 2 Sept 2022
Ghost Update: 5 Sept 2022
Ghost Update: 6 Sept 2022
Ghost Update: 7 Sept 2022
Ghost Update: 8 Sept 2022
Ghost Update: 9 Sept 2022
Ghost Update: 12 Sept 2022
Ghost Update: 13 Sept 2022
Ghost Update: 15 Sept 2022
Ghost Update: 16 Sept 2022
Phoned In: 16 Sept 2022 - Agent reports only CSIS Remaining as of 7 Aug.
Ghost Update: 21 Sept 2022
Ghost Update: 22 Sept 2022
Ghost Update: 23 Sept 2022
Ghost Update: 26 Sept 2022
Ghost Update: 27 Sept 2022
Ghost Update: 29 Sept 2022
Ghost Update: 3 Oct 2022
On 16 Sept the agent said that all updates from 7 Aug to 16 Sept were all related to the security checks.
I hope this information is of some help to those that are confused about the updates, and I wish all of us a quick PPR and approval process.