I ran into something similar when I first set this up. One thing that caught me out was that the placeholder on its own wasn’t enough. I had to make sure the correct answer was actually defined for every question, then check that the quiz results page was configured to display answer feedback. It’s also worth confirming that the option to show answers after submission is enabled, because if that’s turned off the variable won’t output anything. If everything looks correct, try clearing any cache and testing in a private browser window, as cached settings can sometimes make it seem like changes haven’t been applied.
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