The data is stored in Microsoft SQL Server. The query tested in Microsoft Management Studio is valid, but ArcCatalog and ArcMap are no longer tolerating the spaces and special characters in the aliases.
ArcGIS & ArcCatalog 10.5
Microsoft SQL Server 2017
I do have ArcGIS & ArcCatalog 10.6 on another VM... haven't tried there.
I also have a support ticket. Thought I'd see if the community had some ideas, too.