SFM Change Control issue

Hello,

I'm using SFM as a virtual appliance for weeks to manage several XG Firewalls and I wanted to use Change Control feature to take snapshot of the Firewalls, and be able to revert back any changes done on the appliances.

I'm managing 9 XG Firewalls through SFM and I turned ON change control on all of them but it doesn't work properly on 4 appliances.

When I try to create a system snapshot, I can see in the system management logs of SFM this event: "The process to create System Snapshot has been initiated successfully." for the 9 devices, but only for 5 devices I can see this one after "System snapshot of Firewall 'Firewall name' taken successfully." But for the 4 last devices this event never happens.

In the Change Control panel of SFM I can see the system snapshot created succesfully for the 5 Firewalls in red color, but for the 4 other Firewalls, the system snapshot never appears in red color, but in grey color after the firewall being deleted and registered back into sfm, but still unusable. 

If I create or delete an item in the Firewall, it shows in the change control and I can click on the "revert" button to revert back the change, but it doens't work for the 4 same Firewalls. I can see the event in the logs of SFM "Initiated the process to revert configuration changes up to 1532076885219" then "Process to revert is completed. Drill down to check the status of each entity." but it stays on "IN PROGRESS" for days and never ends... 

I already tried to delete the faulty firewalls from SFM and register them again, tried to disable and enable back change control but the issue is still there...

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Thank you for your help.