@EggandNog
Could you explain further what is not working well in regards to the tool? Do you see a difference in the measuring tool within the map widget or measurement widget?
Are you comparing data in your attribute table to what is being shown on the measurement tool?
There are two different measurements, one looks at the geodesic length and the other is planar measurements. See the documentation below for more information, it is logged under ArcGIS Pro but the theory is the same:
https://pro.arcgis.com/en/pro-app/latest/tool-reference/spatial-analyst/geodesic-versus-planar-dista...
