Wiki TOC isn't rendering

For some reason [[_TOC_]] isn't rendering on our wiki pages.

Here's how it looks in Gollum:

gollum

And how it looks in Gitlab:

gitlab

Broken links

I've also noticed that external links seem to be rendering as relative links. In the example below the hyper link is to an external smb server (it's the same for local files) called files, but Gitlab seems to append the path to the end of the URL:

external_links