there are some known HLS issues similar to what you are describing with the initial release of 6.1 firmware. Go to settings, check for updates, see if you can get a newer firmware release. We've done a partial release of a newer firmware version, and we are waiting to see if any issues are reported on those devices before we finish rolling it out.
Also, make sure to set your bitrate to zero if you are not using a master playlist file.
- Joel