I think it’s similar to what I encountered before (see the discussion). As far as I can remember, most of the time it happened when I was trying to save the file, but there were likely instances caused by the automatic saving mechanism as well.
In the past two weeks, I encountered a similar situation to @jonsterling’s once. When I switched to Bike from another app (using Command + Tab), I found that it was unresponsive (the spinning beach ball appeared). In the end, I had to force quit the app, and the data was lost.