Project Wiki - Sub-page creation broken?

Project Wiki - Sub-page creation broken?

Having just set up my Zoho account, I am trying to create a basic wiki structure so that my team can begin populating it. I was initially able to create both pages at the root level and sub-pages (well, one sub-page, anyway).

Now, however, something appears to be broken. When I attempt to add a sub-page, I am presented with the dialog box for name/type/location, as usual. But when I click 'create', instead of loading the editor for the sub-page, I am simply returned to my previous position in the wiki, and the sub-page I have attempted to create does not appear anywhere in the wiki or site map.