When select the center of the arc or circle, please press TAB button on Keyboard. Publisher is a 3D software, and it support 3D dimension, it dimension the point to Point distance, if you want to Point to Line distance, please place the dimension and click the little button near the dimension, it will change to align.
Hope this helps. In image 2, the dimension is 17.68, this dimension is point to point. in image 3, the dimension is 17.52, it is point to line.
Peggy Wang Sr. Software QA Engineer Publisher Quality Assurance Team Autodesk, Inc.