I have several cards with text under the “Back Extra” box, downloaded from my medical school. I’m usually able to see the text but for some reason, I am no longer able to see anything in the ‘Back Extra’ box of each card.
For instance, I have an image of the back side of a card below as well as what it looks like to edit.
I have followed the advice of other posts and added an {{Extra}} on the beginning or end of the code for the Back of Card, but that doesn’t work either.
A field replacement is the right way to do it – Field Replacements - Anki Manual – but it needs to match the name of the field you want to show on the card. In your case: {{Back Extra}}.