We're aware of an issue which causes the Task Log window to appear blank when running on Mac OS 10.9 Mavericks. First, your data IS safe. The issue is that it isn't displayed, but it's still there, and it's not going anywhere. Second, we are working as quickly as we can to address the issue and submit an update.
We thank you for your patience and apologize for the inconvenience.
Update: We've just submitted an update (v1.1.2) which fixes the Mavericks issues. We've asked Apple to expedite the review, so it should be available in the next day or two. Thanks, everyone, for your patience!