I've noticed when running WordPress in certain situations (i.e. CentOS via Vagrant) that the auto-update feature stops reporting available updates. For instance, I'm running a site at WordPress 3.3.2 and I know there are multiple plugin updates, but when I go to the Updates section of the Admin, it tells me everything is up to date. I can manually click to check for updates, and still it doesn't report anything.
Any ideas on how to fix / troubleshoot this?