AP Invoice Approval layout missing from approval email notification

Summary:

Created customised AP Invoice Approval notification layout and was appearing in the notification email.

After removing all layouts, including delivered, from the custom directory then uploading the final version. Subsequent emails notifications no longer contained the layout and was asked to login to approve. Refer to image below where the yellow circle is where the layout should appear.

I am assume that the reason for the empty email is due to the missing delivered layout.

Question:

How do I correct this issue?