There is a possibility that your ESG may become unmanageable after upgrading NSX Manager to 6.4.4.

Before upgrading to NSX 6.4.4, please make sure you have the VMware KB67416before you begin!

NSX Manager and the ESG experience problems in the message bus communication channel when grouping objects such as security groups or IP sets are used in ESG firewall rules.

Additionally, problems can occur when firewall rules containing grouping elements are applied to ESGs.

Additionally, problems can occur when firewall rules containing grouping elements are applied to ESGs.

If such grouping objects are used in your environment, contact VMware support before upgrading. VMware support could provide a hotfix.
If the upgrade has already been performed, the hotfix can also resolve the issue. However, the ESGs will have to be redistributed for this.