Simple Form Post Not Working

Isn't it "public function __construct()" (with two underscores)?

Also, why use "session_start()" (native php function), and then use "$this->session->userdata" (CodeIgniter specific method)? Why not load the session library and then remain using the library all the way around?

...Also, related to the "$this->web_app_model->getLoginData($u, $p);" error. Did you load the model before using it?

I was following a tutorial from YouTube for getting mu authentication working. Both the single underscore and the session_start() method came from that tutorial and of course in the tutorial they do not encounter the issue I am having.

I am loading the web_app_model in in the config/autoload.php file.

Any similar occurrences of my issue I've found on google refer to issues with .htaccess and mod_rewrite but I have all of that setup and working as recommended. 

What seems interesting to me still is that post data is available via $_POST but not vie the Codeigniter method.

I am using the latest 3.1.8 build running on XAMPP 5.6.35

Is there some other Global step anyone can identify that could be causing this to fail?