I had this problem with tags. I edited the code in the file Ad.php in the folder advertising-manager/lib/OX/Ad.php.
If tags weren’t defined, and if I had unclicked ‘tags’ for a particular ad, it would throw an error. I just added an if statement to test that it had a tag before it processes the foreach statement.
//add the if statement because if $tags wasn't defined it was throwing an error
if ($tags) {
foreach ($tags as $tag) {
if (in_array($tag->term_id, $tagFilter)) {
$found = true;
break;
}
}
}
This solved a similar issue for me.