Hera is an example, http://www.babylonjs-playground.com/#1BKDEO#43
I created two worldspacecanvas named canv1 and canv2, In the beginning, canv2 is over can1, but canv2 will be under canv1 when canv2.position is reset.
It happens on using FreeCamera, AcrRotateCamera is no problem.
Is it a bug ? @Nockawa