Stop the program reverting out of mask mode when switching layers

Why does Painter insist on going back to base color from mask mode when I switch layers?

Working in mask mode is often the quickest way to see which surfaces in a complex scene have which materials, but every time I switch layers it jumps back to base color. This is really disruptive to workflow.

With a complex scene with many layers, keeping track of material assignment is already extremely difficult in Painter and it's important to try to avoid overlapping materials. So masking is very important. Working in mask mode to quickly check thru all layers in this way would really be the fastest method... except Painter jumps out of this mode with every layer change, and all the associated redraw time that this entails. Think I really might have to learn Mari.....