A potential bug fix has been published today. On a slow mobile connection it could happen that the Story dialog would fail to load (during a flashcard review). In that case I'm told that tapping in the empty space would not close the dialog as it should.

For mobile view, I changed the Story dialog to always display a Close button while it is loading. I couldn't reproduce the original issue, so I hope this works. Let me know if there are still issues or if this works better, Issue 106 on Github.