Issue
Clicking "Automatically copy over from HTML" or "Copy from HTML" in the Email Editor fails to copy the contents over to the Text Only version of the email.
Solution
This can occur if there are no editable sections in the email asset. By default, Marketo automatically copies the text content of any Rich Text element that’s in your email over to the Text version.
Marketo defines a Rich Text element inside of an email template as a section using either mktEditable or mktoText classes. If the email's HTML does not contain either class, then no content would automatically be copied over.
Here is additional documentation related to Email Text Versions: https://experienceleague.adobe.com/docs/marketo/using/product-docs/email-marketing/general/creating-...
A quick workaround would be to manually copy and paste the content you wish in the Text Version, and in the future build/use templates to make emails with editable sections.
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