I'm currently working with a plugin ( Easy Outline: https://www.assetstore.unity3d.com/en/#!/content/62384 ) that seems to conflict with the Wikitude Camera script. I managed to isolate the issue to calling Camera.main.render() during LateUpdate. This happens only when the Wikitude Camera script is also attached to the camera. As Wikitude Camera is closed source, I was unable to go any further with debugging.
The problem is weird flickering in the Editor window (not limited to the Game tab even). See attached video for an example. I'm using Unity 5.6.1f1.