PHP Validation options remain in view even after being removed via the views ui.

I used a views php validation for a contextual filter:
"Content: NID" > "Provide default value" > "Content ID from URL" > "Validation Criteria" > PHP

$node = menu_get_object();
if (isset($node->field_quiz)) {
  $quiz_nid = $node->field_quiz['und'][0]['target_id'];
  $quiz_node = node_load($quiz_nid); 
  return quiz_take_access($quiz_node); 
}
return false;

This was set in the master, but I was over-riding it on all views displays but one. When I tried to remove it to test if this was the issue described below, it was not seen in any of the displays, but was still in the master, and in cache. I removed it from the master, but it was still present in the view, in cache, and still in there when exporting the view.

Using:
Drupal 7.35
Views 7.x-3.10
Panels 7.x-3.5
Ctools 7.x-1.7
Views php 7.x-1.0-alpha1

Originally titled "Views content pane not showing in panel for some users", as that was the symptom. The original symptom I was experience is as follows:

I have a view content pane displaying a node of a certain content type. This content type contains entity reference fields which are rendered as nodes on in the view field settings. On this view, I have a contextual filter of type "Content: NID" with "Provide default value" selected and "Content ID from URL" selected in the drop-down.

I created a panel page over-riding the node template, and a variant with 2 selection rules: 1) Node being viewed is this content type, and 2) "Node: accessible - Logged in user can view Node being viewed."

I am using two users to test - the admin user, and a test user.

1. When I view this panel page as an admin, with 'bypass node access' permission, I can see the panel with the content pane, and the node and the referenced nodes that are present in the view.
2. In the node access table, the node is listed with the correct realm and gid.
3. Debugging output shows that my test user has the correct grants (at least one grant contains realm and gid that matches the node_access records), and should be able to view the node.
4. If I disable the panel, my test user CAN access the node directly, as well as the nodes referenced in the entity reference fields.
5. I made a copy of the content pane display (as a view page, with url), and my test user CAN access the view, and all nodes on the view.
6. When my test user tries to view the panel page, he sees the OTHER panes on the panel (which I assume tells me that "logged in user can view node being viewed" is TRUE, as the variant IS being displayed).
7. One strange thing that I noticed, is that when I try to preview the content pane display by manually adding the NID argument, I get nothing - no query being displayed, and no content being rendered, but this is for the content pane, not the view page display with url. Adding the NID argument on the page display presents the preview correctly.

The test user can NOT see the views content pane embedded in the panel, while the admin user can. The pane simply does not render, and the "No results behaviour" of the view, which is set to display a message, does not render, either. It is just blank.

Anyone know why the content pane would not render? Is there some permission that I'm missing, or some setting on the views content pane screen? Or some setting on the panel variant configuration, or the pane configuration? I don't see anything that should hide this pane, and I don't understand why it isn't being rendered.