Use lastInsertId() multiple times on different queries in transaction - php

Question

So I've been trying to find an answer but I don't think there is one that is specified to what I am trying to do. I will start with my sample of code
file.php
$q = "INSERT INTO ".PORTAL_DB.".resource_file (company__id, rf_category__id, title, file_name, description, path, upload_by, has_quiz)
SELECT ?, ?, ?, CONCAT(MAX(id)+1, '.', '$extension'), ?, ?, ?, ? FROM ".PORTAL_DB.".resource_file";
$stmt = $CONN->prepare($q);
$filename = 0;
$resource_file__id = 0;
if($stmt->execute(array($company__id, $rf_category__id, $title, $description, "assets/$uploadFolder/", USER, $has_quiz))){
$filename = $CONN->lastInsertId();
$resource_file__id = $filename;
}
if(!empty($quiz)){
$passing_score = $quiz->passing_score;
if(!is_numeric($passing_score) or ($passing_score < 0) or $passing_score > 100){
$CONN->rollback();
throw new Exception("Invalid passing score value for quiz, please fix");
}
$q = "INSERT INTO ".PORTAL_DB.".rf_quiz (resource_file__id, passing_score)
VALUES(?, ?)";
$stmt = $CONN->prepare($q);
$rf_quiz__id = 0;
$stmt->execute(array($resource_file__id, $passing_score));
print_r($CONN->lastInsertId);
exit;
$question_ids = array();
foreach($quiz as $qz){
$question = $qz->question;
//print_r($qz);
$q = "INSERT INTO ".PORTAL_DB.".rf_quiz_question (rf_quiz__id, question)
VALUES(?, ?)";
$stmt = $CONN->prepare($q);
if($stmt->execute(array($rf_quiz__id, $question))){
array_push($question_ids, $CONN->lastInsertId);
}
}
//print_r($question_ids);
exit; // using this for testing only
}
explanation
The above code is called after $CONN->beginTransaction() so that I can manage errors easier. From what I understand you can call the stamtement $CONN->lastInsertId() multiple times without issue, however I can get the first id which is stored under the variable $resource_fild__id then when we go down to the $rf_quiz__id variable, even if the call is successful, I get nothing and it causes an error. I want to be able to do all of this in one transaction for the ease of the coding process and organization.
I hope someone can point me in the right direction, or at least be able to tell me what I am doing wrong so that I can find a fast solution!
Thank you for all help in advance.