On mac if you load a binary image nothing is displayed and the widget planes in 3D disappear. Just their red, green and blue borders stay visible. (Attachement "Load Binary")
IF you create a new segmentation the 3D planed turn black. You can draw into 2D and as long as outline binary is turned on the segmentation is shown in 2D but never in 3D.
If you change the opacity of the grey value image the grey value image disappears immediately.