checkForPlagiarism()

function checkForPlagiarism (answers, textToCheck) {

  for ( i = 0; i < answers.length; i++) {
    let studentresponses = answers[i];
    if (studentresponses.response.includes(textToCheck) && studentresponses.isEssayQuestion === true) {  
      return true;
    }
   }
   return false;
}

function checkForPlagiarism(answers, snippet) {
  let foundAnswer = 0;
  let result = false;
  for (let i=0; i<answers.length; i++) {
    if (answers[i].response.includes(snippet)) {
      foundAnswer = i;
      result = true;
      break;
    }
  }
  if (result && answers[foundAnswer].isEssayQuestion) {
    return true;
  }
  return false;
}

I got it! The submission was tripping over identifying the snippet in both non essay and essay questions. This pulls all the essay questions into a storage array and then checks those, which removes the non-essay questions all together.

function checkForPlagiarism(answers, snippet) {
let essayArray =[]
for (let i=0; i<answers.length; i++) {
if(answers[i].isEssayQuestion){
essayArray.push(answers[i])
}
}
for (let i = 0; i<essayArray.length; i++){
if (essayArray[i].response.includes(snippet)) {
return true;
}
}
return false;
}