When working with Form fields or hyperlinks whether within a linked Table of Contents or stand alone links, always activate the Tag Annotations option.
It is helpful to activate Tag Annotations prior to using the Acrobat Auto Tag feature as well to bring across any form fields.
Once activated, the Tag Annotations option will automatically create the Link Object tag for stand alone links to web pages and email address and Table of Content page navigation links.
To activate, right-click any tag in the tag tree and select Tag Annotations from the context-sensitive pop-up list.