In 3d Mode, Can't view the layers that I'm drawing on

When I’m in a shot that’s 3d, I’m trying to draw on layers in Camera View. But when I switch to Brush tool the drawing disappears behind all 3d elements, even if the layer is on top! Fortunately when I use the Pencil tool, the layer stays visible in front of the Camera like it should be.
Why is are the elements in my drawing layer disappearing behind the 3d elements when I have brush tool toggled? To get around this I actually have to toggle off the visibility of 3D layers.

This makes boarding in 3d mode difficult because the Pencil tool isn’t my main drawing tool.
Is there any preference check box that I should have toggled?

Also be aware that if your drawing layer is not directly facing the camera, you will be prevented from drawing; drawing is prevented due to the extreme perspective effects that happen when the drawing is not directly facing the camera.

This is if you’re in the 3D/Perspective view and have rotated the element.

Check to see whether you have Draw Behind enabled on the Brush.|Chapter%206%3A%20Drawing|_____7