I am trying to use the Alter Field geoprocessing tool to change a field name of a feature glass in a geodatabase. I'm trying to change the field from Total_Mdollars to Total_MDollars. The tool completes "successfully" but the field name remains unchanged. Anyone else having this issue? I think its a bug. The field contains values but according to the docs this should not matter when changing the field name. I've tried it in Pro, ArcMap 10.5.1, and via Python.