I don't have Professional but in my experience with moving to newer versions of Visio, the shapes in stencils are sometimes changed which gives different behaviour.

If you open an old legacy file which contained a shape that behaved the way you liked, it will probably still behave that way in your new version of Visio. If so, you could then stick that into your new stencil and choose it rather than the new 'improved' version.

It is also possible that the shape gets its accuracy and units from a page or document level setting. The only way to work this out is to look at the shape's shapesheet and figure out what it has been configured to do. If you post a sample document with the new and legacy instances of the shape we can look at the settings to see where the differences lie.

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Andrew Lockton
Chrysalis Design, Melbourne Australia