We couldn't reproduce this issue internally
What version of the Wikitude SDK and Unity are you using and on which device are you testing? Do you get any errors in the console log? Were there any modifications made to the sample? Do you have the same issue with the Advanced Custom Camera sample?
For the purpose of having custom input, I am trying "Plugin - Simple Custom Camera Scene" from Wikitude Samples. I am noticing some strange behavior. In unity player, upon running the scene I initially see camera live output. But, once the tracker image is identified the camera stream hangs but the tracking works fine. Upon moving the tracker in real world, Wikitude can track it and the eye in virtual scene moves but camera stream is not updated.
Am I missing something?