The Add Geometry Attributes tool in ArcGIS Pro 1.3 hangs the application after I put in a feature class that is in State Plane feet. The map is in WGS84. I then get the endless spinning wheel. The feature class is in a geodatabase and only has 170 records. The Add XY coordinate tool works though. I do miss the Calculate Field geometry in ArcMap.
As others suggested !SHAPE.CENTROID.X! and !SHAPE.CENTROID.Y! in the field calculator work too provided you don't have any records that have null shape. If you do you get an NoneType error and nothing happens. In ArcMap 10.4.1 when this occurred you get your results up to the point of the first null shape and then no X or Y results after plus you get the error message. The latter helped me figure out why it was going wrong.
I've encountered the endless spinning wheel during other operations in ArcPro 1.3 on a Windows 7 computer.. It would be nice if you could somehow stop it and continue instead of having to shutdown the application.