There is this page http://vaemendis.net/ubooquity/static7/sharing-a-calibre-library It's accessible through the FAQ questions about calibre.

Sweet, thank you for adding this in. Works great.

One I noted this occurs with is slashes in the comic title

In the admin section, try pulling the error log. You might have an error similar to the one I saw, that should help Tom narrow down what the issue is.

I tried adding another folder and another user. The second user similarly does not get any content. and it is the same with the second folder, does not show content.

The only log messages that seems like it could be related was 

"20150305 15:20:59 [Scanner thread] WARN com.ubooquity.data.database.b - Could not find id of root path /shares/Installs/Comics (ignore this warning if you just added a new root directory)"
It only happens when beginning a scan.

And "20150305 15:25:03 [pool-2-thread-16] WARN com.ubooquity.provider.page.a - Entry not available, either you don't have the right to see it or it is a file format not supported for online reading. ID: 1747"
This occured when I went straight to a book in the comic reader "/comicreader/1747" that I had previously visited when security was turned off.

I hope that information helps.

I'm bumping this. I have the same issue of no content when user security enabled on 1.7.0. No error message just no content. Works fine with security off, but I don't want to leave it like that since I'm running it from a home server. Below are my settings for Comics.

Along with this, an indicator of whether the comic has been read or not. I'm thinking a badge indicating it's been read. Sometimes I read multiple issues in a row and then the next day I can't remember which one I left off on.