Failed to add data: Secured feature service proxied through ArcGIS Online

[ElliottPlack1]

I am getting a "Failed to add data." error when adding a feature service via the Catalog Pane under Portal. The feature service is added by URL on ArcGIS Online because it is a secured feature service and the username/password are stored in the feature service definition. The secured feature service is published via ArcGIS Server 10.4.1 and contains data that is push/pulled through a firewall to an ArcSDE database (versioned) on Oracle install. Screenshot attached.

In earlier testing, the workflow of adding AGOL-powered feature services via Catalog/Portal worked, but the secure feature service was hosted on ArcGIS Server 10.5.1. Currently, as a potential workaround, I can add the source REST URL of the secured feature service to ArcGIS Pro without issue, but I do not want to hand out the username and password to users. I can also add that same proxied feature service to ArcGIS Pro when it is running on the network where the data originates. Adding it to ArcMap as a hosted service works.And of course, I can view/edit this proxied feature service using web maps, Collector, Survey123, etc.

What is causing the add data error when trying to add the data to ArcGIS Pro? Pro is at v2.1.2.

[ZackArno]

Has anyone figured this out yet?

[ElliottPlack1]

We ended up abandoning the approach where we'd use ArcGIS Pro for editing. I have not tried it recently, have you?

[ChristopherEby2]

I have this issue and I'm hosting my Feature Service on AGS 10.6.1. I'm also using Pro 2.5.

[JoeBryant1]

I'm having this same issue now (I didn't think this used to be an issue so I'm trying to determine what changed). I'm trying to add Living Atlas map services to an ArcGIS Pro map while logged into our Enterprise Portal. The services appear in the pre-filtered list for our organization, but I get a "Failed to add data: ..." error when I drag the service into the map.

We are on Pro 2.7.0 and Enterprise 10.6.1.

EDIT: My ArcGIS Online organization password had changed, so the credentials stored in Enterprise to access subscriber content no longer worked. Once I updated the credentials in the ArcGIS Online settings tab in Enterprise, the issue was fixed.