I’ve the same issue. Creating a document from inside a group (via “Create New Doc” button or “There are no docs for this view”. Why not create one?” link) doesn’t work.
It points to http://www.mysite.com/docs/create/?group=marketing which gives a 404.
Using the general http://www.mysite.com/docs/create/ works.
After a bit of playing around, I got it to create docs inside a group using this link http://www.mysite.com/groups/marketing/docs/create/?group=marketing
Just don’t know where to change it in the code 🙁