If the above does not work, you may have to score the test yourself before going to the Results page. If it were me I would have a special version of the Next button on the last question. It would have actions like these:
1. Clear a counter variable to 0.
2. Add 1 to counter if (Condition tab) the first question variable is correct.
3. Add 1 to counter if the second question variable is correct.
4. ... for the rest of the questions
5. Submit/Score test if the counter variable was >= whatever 80% would be Else go to a page that told them that they did not pass (and contained a button to take them to wherever you wanted them to go.)
