This problem has been resolved in a published completed on 8/25/2015 to Hosted TechSmith Relay instances. If you are still experiencing this issue, please open the Relay Recorder, and you should be prompted to download and install the update to fix this problem.
Recording the screen looks fine, but after stopping the recording the preview window shows only a black screen and the cursor. The video will publish black also.
For the hosted version of TechSmith Relay:
This issue will be addressed in a release in the near future. Recorders will need to be updated with the latest release after the fix has been published.