I just did a fresh install of MediaWiki-Vagrant on OS X 10.11.3. After adding visualeditor to the enabled roles and provisioning the VM (multiple times), the Edit tab is still not available and VE seems nowhere to be found.
Note that I haven't enabled the parsoid role, since according to https://www.mediawiki.org/wiki/Parsoid it isn't necessary. Also since moving to RESTBase I've heard this role has been deprecated.
Another weird thing is that I can actually invoke the VE loading bar through injecting veaction=edit in the query string, but it hangs midway through the loading and throws a 503 error.