There is a known licensing schema oddity when upgrading from Forms Standard to Forms Enterprise, that could cause issues for a few customers running older versions of our Forms product.

 If you are running Nintex Forms Version 1.9 or less, for SharePoint 2010, or version 2.7 for SharePoint 2013, then you will need to upgrade your environment first, to the latest build of Forms, using a Standard Forms license in the environment, then then import your Forms Enterprise license.

Everything moving forward will then work as expected.