Field widget value not able to save via ajax
There might be a few issues, but it hard to tell.

First make sure the field is actually on the node. (Source https://www.drupal.org/documentation/entity-metadata-wrappers):

function _wrapper_debug($w) {
  $values = array();
  foreach ($w-&gt;getPropertyInfo() as $key =&gt; $val) {
    $values[$key] = $w-&gt;$key-&gt;value();
  }
  return $values;
}

dpm(_wrapper_debug($some_wrapped_object));


If it is there, perhaps you made the field a multi value field (it can hold more then 1 value), in this case you need to assign it like this:

 $node_wrapper-&gt;field_log[]-&gt;set(1); // Note the extra []


If this does not solve the problem, have a look at the above metadata wrapper page. It comes with a lot of examples en explanations.