Okay so inside my game I put my webcam in successfully, it loads and I can see myself when I run the game from inside Unity.
But… When I Build+Run the game, it breaks the webcam and doesn’t work
Can anyone help?
Had the same problem today, and solved it quite simply. I guess I was lucky. 
Here’s my setup:
- I’m using Screen Space - Camera canvas
- I have RawTexture inside
- Everything works in Editor.
What solved the problem for me was Plane Distance.
Since Camera has Far clipping plane set at 1000, I’ve set the canvas Plane Distance to 1000, and canvas is automatically moved to 990 on the z-axis.
When I changed Plane Distance to 950 (number smaller than 1000, experiment), the problem was solved when I’ve built the application.
Hope this helps!