It seems that sub folders are not supported.
Browsing to https://gitlab/namespace/project/wikis/subfolder/page will bring you to the "edit mode" with an empty document (albeit "page" having some content).
It also seems like using GFM prevent making links to images within the repository (at least they are not displayed).
Subfolders are indeed not yet supported when viewing within Gitlab. I left out support for most of the advanced Gollum features on the first pull request for several reasons.
I do hope to eventually support all of Gollum's advanced functionality. It's taken quite a bit of work just to get here. I hope that with the blessing of the core maintainers we can continue to improve upon the Wiki system.
Lastly, if there is a feature that you wish to see supported, pull requests are very much appreciated. I have already spent quite a few hours just implementing the base functionality. I do plan on layering on the rest of the Gollum goodness, it just may take me quite awhile.
In a rush... had to make several grammar edits... sorry for the extra emails.*
Thanks Dan for taking the time to reply.
I initially opened the issue because i wasn't sure if that was the expected behavior… or not.
No doubt a Gollum integration is lots of work (thanks again!) and having your initial PR merged is already a big step forward.
Unfortunately, i won't be able to help coding (ruby ain't my cup of tea).