how to get all the values in an edit form
The form_state-&gt;getValues() only works during the validation and submit process. Instead you need to look to the $form variable for values. Unfortunately you cannot get all the values easily you must dig into the form itself:

$form['title']['widget'][0]['value']['default_value'];


EDIT
I was looking into this more and there may be a cleaner way.

First you must get the form object from the $form_state variable. From there you can use the function getEntity() to actually get the entity that the form is editing. Then if you want to get a value you can use the get('field_name') method or if you want all the values use toArray()

// Get the entire node as an array and will include all values
$node = $form_state-&gt;getFormObject()-&gt;getEntity()-&gt;toArray();


or 

// Get the entity object
$node = $form_state-&gt;getFormObject()-&gt;getEntity();

// Get the field
$node-&gt;get('field_my_field');

// Get the field as a string (returns value)
$node-&gt;get('field_my_field')-&gt;getString();