Thanks to this post I found a temporary solution. In add-meta-tags.php (wp-content/plugins/add-meta-tags) I added:
elseif ( $def_key == 'auto_description' || $def_key == 'auto_keywords' ) {
if( !isset($_POST[$def_key]) ){
$add_meta_tags_opts[$def_key] = 0;
}
}
So starting at line 177 it looks like the following:
if (isset($_POST['info_update'])) {
// Update settings
$add_meta_tags_opts = array();
foreach ($default_options as $def_key => $def_value) {
// **Always** use the <code></code>settings_version<code></code> from the defaults
if ($def_key == 'settings_version') {
$add_meta_tags_opts['settings_version'] = $def_value;
}
// Add options from the POST request (saved by the user)
elseif ( array_key_exists($def_key, $_POST) ) {
$add_meta_tags_opts[$def_key] = $_POST[$def_key];
}
// here is my fix
elseif ( $def_key == 'auto_description' || $def_key == 'auto_keywords' ) {
if( !isset($_POST[$def_key]) ){
$add_meta_tags_opts[$def_key] = 0;
}
}
// If missing (eg checkboxes), use the default value
else {
$add_meta_tags_opts[$def_key] = $def_value;
}
}
// Finally update the Add-Meta-Tags options.
update_option("add_meta_tags_opts", $add_meta_tags_opts);
//var_dump($_POST);
//var_dump($add_meta_tags_opts);
amt_show_info_msg(__('Add-Meta-Tags options saved', 'add-meta-tags'));
}
$default_options
Array
(
[settings_version] => 2
[site_description] =>
[site_keywords] =>
[global_keywords] =>
[site_wide_meta] =>
[auto_description] => 1
[auto_keywords] => 1
[auto_opengraph] => 0
[auto_dublincore] => 0
[noodp_description] => 0
[noindex_search_results] => 1
[noindex_date_archives] => 0
[noindex_category_archives] => 0
[noindex_tag_archives] => 0
[noindex_author_archives] => 0
[copyright_url] =>
[default_image_url] =>
[i_have_donated] => 0
)