I'm currently experiencing a very illogical problem.
I'm using the CodeIgniter SQL query builder and I've written a SELECT query with this condition:
$sql->where("utm_source != 'WELCOMING'");
The problem is that if the utm_source column is NULL, it won't be returned. If I fill it with something random like "test", it'll be returned. I don't understand what's going on, this SQL query works perfectly locally, but it bugs in the staging server.
And MySQL versions are exactly the same in local and staging (5.7.35).