Hi,
I’ve noticed the problem when Piklist used with SiteOrigin page builder plugin…
It’s not possible to save SiteOrigin composed page with any other Custom Template but default one. “class-piklist-revision.php” file is the only one using ‘save_post’ WP hook/action with the very strange priority of -1 (haven’t seen anything alike yet nor I know the purpose of it). Later priority solves the problem tho!
add_action('save_post', array('piklist_revision', 'save_post'), 99, 2);
The latest Piklist 0.10 beta suffers from the same problem!