SELECT count(*) with where produces weird values - mysql

Question

It seems when I am trying to make a query to get the users transaction sum, it does not return the proper value until I remove the filter on code, what is even more interesting is the filter on the bar code following works perfectly fine, it seems maybe there is an inconsistency between both the subqueries in the WHERE clause?
Explanation:
With the below query, when I remove the and code != "foo" AND code !="foobar" from the query, it returns the correct value, but I also tried changing it to code = "foo" or code = "foobar" to check if any of the results had these codes, and it returns null when I do this.
SELECT SUM(t.amount)
FROM transactions t
WHERE `t`.`deleted_at` IS NULL
AND `t`.`user_id` = 80
AND `t`.`user_id` IS NOT NULL
AND `manually_deleted_at` IS NULL
AND
(SELECT count(*)
FROM `transaction_subcategories` s
WHERE `t`.`transaction_subcategory_id` = `s`.`id`
AND `code` != "foo"
AND `code` != "foobar"
AND
(SELECT count(*)
FROM `transaction_categories` c
INNER JOIN `transaction_categories_transaction_subcategories` sc ON `c`.`id` = `sc`.`transaction_category_id`
WHERE `sc`.`transaction_subcategory_id` = `s`.`id`
AND `code` = "bar") >= 1) >= 1
AND `posted_date` BETWEEN "2016-04-01 00:00:00.000000" AND "2017-03-31 23:59:59.000000"
AND `parent_id` = 0;
While I do realize this is a mysql query issue, the laravel ORM code is a bit cleaner:
$income_transactions = \Auth::user ()->transactions ()
->notManuallyDeleted()
->whereHas('transactionSubcategory', function ($query) {
$query
->where('code', '!=', 'foo')
->where('code', '!=', 'foobar')
->whereHas('transactionCategories', function ($query2){
$query2->where('code', '=', 'bar');
});
})
->whereBetween ( 'posted_date', [$from,$to])
->where('parent_id', '=', 0)
->get ();
Update
Not sure if this helps, but I did a query to see which subcategories it is returning with the WHERE clause and it returns only ones where the code is NULL
mysql> SELECT * FROM transaction_subcategories WHERE id in ('1125', '630', '1395') AND code is null;
+------+-----------------------------------+------+---------+
| id | name | code | user_id |
+------+-----------------------------------+------+---------+
| 630 | foo | NULL | 80 |
| 1125 | foo | NULL | 80 |
| 1395 | foo | NULL | 80 |
+------+-----------------------------------+------+---------+
Update 2 Turns out it is the WHERE doing it, it seems that NULL values won't be compared against a string, in other words if I do a WHERE on a column that has nulls, the null value rows will disappear
Answer Turns out adding OR code is null in a group in the WHERE clause was all I needed. Closed :)