Updated security rule fails to delete after instance termination

Here are the steps to recreate,

1)create a SG and add rules
2)Spawn a VM with that SG (corresponding flows seen)
3)Now modify the SG to add a new rule (corresponding flows seen)
4)Disassociate the SG from the VM
The newly added rule does not get deleted.Only the old rules are deleted.
Similarly, even when the VM is terminated the newly added rule fails to get deleted.