Hi,
I am creating some custom Visio product icons. They look as I am creating them on my device, but when I pass the file to others the shapes are being given a theme or effect when dragged onto the page.
Is there a way to create masters that are set up so effects or themes aren't applied to them?
Sure. you can "protect" your shapes from themes.
You can even choose the unwanted theme options you want to protect your shapes from: from theme colors, theme borders, etc, or every theme aspect.
You need to turn on developer mode, select the shape and use command "protection" from the developer tab.
Alternatively, you can set protection in shape's shapesheet directly (look for the "protection" section)