When editing a task form using SharePoint form library, the page may fail to load and display the following message indefinitely:
Nintex Forms for Office 365 is loading...
"Nintex Forms for Office 365 is loading..."
This is a known issue that is currently under investigation.
There are several list types in SharePoint Online that we don’t support with Forms. SharePoint Form Library isn’t supported, as Form libraries inherently hold xml forms (they were designed to be used with InfoPath forms), and don’t use the standard aspx pages that Nintex uses when uploading/creating items within a Form Library.