Segmentation (problem with drawing on a label map)

Hi everyone,

I’m using the 3D Slicer to make segmentation based on T1 images. I have select by drawing the white matter and then the grey one. While I was drawing the cerebellum, I made a quick recheck of what was already done in the cortex and suddenly all the areas that I’ve drawn disappear. The grey and white matter are used as a label map and T1 images from MRI are used as the master volume.

Does anyone know what could be the cause of the invisibility of what I draw before.

Do you use the latest nightly version of Slicer?