This is #1 of 2 bugs that I consider “urgent” in that the longer they are not fixed, the more “entropy” they will generate which will be increasingly hard to remove once the features will work again.
This 1st bug has already been described in Bug: Bookmarks window is empty, so I just need to remind of it. The problem here is that you cannot reorder the entries via drag&drop in the browser window, only in the separate, dedicated window which currently does not work/is empty.
So, with the continued usage of OmniWeb, the bookmarks will become more and more disordered (which will be hard to undo once the disorder reaches a certain level).