Empty security groups OF tables after restarting ODL and deleting some files from inventory

Overview:
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On working devstack (i.e. ping works from VM to VM on internal network) restarting ODL caused security groups tables (41, 42) to be empty

Steps:
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• Load devstack
• Create networks, VMs
• Check ping connectivity
• Restart ODL (see below what is included in restarting the ODL)
• Delete networks, VMs
• Create networks, VMs
• Check ping connectivity

Expected Results:
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• Ping connectivity exists after restarting the ODL

Actual results:
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• No ping between VMs

Logs:

Local in centos-devel/mnt/mpr-dev/pub/Mickael/[bug-id]