Unable to Get the Table. General Function Failure.

[AndrewHargreaves1]

I am using Pro 2.7.1 and secured Feature Services and ArcGIS Server v10.7.1.

I am unbale to access the attribute tables 'design' view in order to assess or update the schema.

I receive the below errors:

@Anonymous User

[ThomasColson]

Need more details. What is the source? Geodatabase? SQL? If so, what flavor of SQL? You cannot change the schema of a feature service, only the data used to publish the service. However, I see that error all the time when there is something going on in SQL that is unsupported by Pro (e.g 2 or more left joins on a view). 

[AndrewHargreaves1]

PostGres. Feature Service from an ArcGIS Server 10.7. This schema is unlocked as shown in screenshot and I'm fairly certain I've added/deleted fields from it before. However, all I want is to be able to open the design view so as to be able to turn on/off fields for easier viewing.