It seems is no longer possible (it was in ArcMap) to Add field to Raster Attribute tables, except through the Add Field geoprocessing tool.
The Add field button in the table window is inactive and it shows the message "This command is currently unavailable. The project has unsaved edits or the table or its schema is read only".
My opinion is that in ArcGIS Pro ArcGIS raster table schema is inactive by default.
Can anyone confirm (or deny) this?
I'm using ArcGIS Pro 2.8 and it's the same in 2.9
integer raster, it works from the toolbox, not the table
The same for me
Build raster attribute table
Go to Fields View
The same for me.
without re-reading and re-checking everything, that is what I think I confirmed.
The probable reason is that the "shortcut" has limitations that only the simplest of cases permits its use and that the shortcut is not a full-fledged access to the tools in ArcToolbox
the "shortcut" is adding a field from the table. It doesn't allow you to specify or check Environments and other influencing factors. Only Tools in ArcToolbox provide the access points to have full control of functionality.
A shortcut will by virtue, have defaults and anything outside of that realm "probably" disables the shortcut.
Hence, I always use tools in arctoolbox (or access tools via python) if the functionality exists there even if a "shortcut" exists.
Historically the tools in arctoolbox have barely changed (except for enhanced functionality and perhaps movement with the toolsets etc). Remember the "visual" transition from ArcMap to ArcGIS Pro... and the "where did X go? where did button Y go? Didn't happen for me since I largely use tools, if available, over shortcuts/buttons