Symptoms:
This is resolved in NSX-T Data Center v3.2.1.
Workaround:
If you have changed the default VNI pool names, revert the names to the original default values :
If you have not changed the default VNI pool names or you are facing issues from changing the name back to the default name(s) now, as you are on NSX-T 3.2.1 or greater, please contact Broadcom Support and refer to this KB article.