If you follow along a freestyle job to completion in the results modal, and then go back to the run in the activity tab, it will show a truncated version of the log in the modal.

If you refresh the page all is ok.

Best to show this with a gif:

http://www.giphy.com/gifs/3oz8xY5FDEd6AlCnNC

Note that I run a freestyle job, then watch it, then close, and open that run. The opened one is truncated.