I normally can edit a master shape in a stencil, but recently ran into a problem with a couple of masters I made. When I open the master for edit, I get an edit window with the master name in the title (for example, control.vssx:Stencil:Relay Contact N.O), but no master shape drawing. If I click on the edit window to open ShapeSheet, I get the ShapeSheet for the page (control.vssx:Stencil:Relay Contact N.O. <Page>). If I pull the master onto the drawing page, I can edit the Shape and ShapeSheet fine. If I pull the instance back into the Stencil to make a new master, I cannot edit it. If I try to edit the instance in the document stencil, I run into the same problem as the original master. What am I doing wrong? Thanks.
Visio Pro 2016
Add on info.
I went to add lines to the original master and found out I could. Then I did some more playing around and open the Diagram Navigation window and I found the original master shape drawing. Guess I need to figure out the diagram navigation and the sheets in the master shape work next.