Question:
Why does Vault fail to create a viewable rendition for an HTML document once the Asset folder is loaded?
Answer:
If Vault creates a viewable rendition of an HTML document (Email Template, Email Fragment) successfully but the rendition fails to generate after the Asset folder is uploaded, Admins should check the syntax of the HTML document for errors. Specifically, Vault does not process the <img> tag of the HTML document until the Asset folder is uploaded, therefore, it is likely that there are errors on lines with this tag.
Related Documentation:
CRM Help Documentation: Creating Approved Email Templates