Admin bar dissapears or won't show for logged in users

My admin bar keeps disappearing and I can't figure out why. It shows on some pages when logged in but not all, especially the home page. I've gone through plugins one by one and tried to find logic in why/how it disappears without any luck.

Latest version of wordpress, NGINX - 8gb cloud server on Rackspace - Multisite

This is affecting the main site only, none of the subsites. I also have a staging site where the problem does not exist, only on the live site.