- Load the stencil, put into edit mode, open the master
- Select the shape's contents (Control-A)
- menu Format -> Layer
- If you are now asked to enter a leyer name then the shape has a blank layer name! Enter a name (anything - it will be removed later) and press OK
- On the Layer dialog click None then OK
- menu View -> Layer Properties and tick Remove Unreferenced Layers, then click OK
- Close the shape, click OK to update the shape
- When done, close the stencil.
(These Instructions for Visio 2003/Visio 2007 - for Visio 2010 the menus are different)