Documents app hangs on file browser. How to export it's files w/o jailbreak?

I used Documents app by Readdle, but now when I open it, it shows me the last document I was reading. When I try to switch back to file browser, it hangs, and I can't press anything. The question is how can I save my files and reinstall the app? Currently it has no updates on App Store.

I tried to use ifunbox and iTunes, but i can only see the "Inbox" folder which is empty. Device is not jailbroken.

PS. This probably happens because the document's name contains unsupported characters.