relationship class created by Survey123 for photo attachments is not "discoverable" in arcmap

[LynnBerni]

We have a FieldParameters survey that was created from an existing feature service on Portal (behind the firewall).  The survey is populating a related table only and has photo attachments. When I look at the data in Catalog I can see the FieldParameters table, the FieldParameters_ATTACH photos table, and the relationship class that was created by Survey123:

What has me concerned is that when I open the FieldParameters table in ArcMap, and then click on the "Related Tables" button, FieldParameters_ATTACH is not in the list.  And it should be, since there's a relationship class. I have to create a relate on-the fly to check my photo attachments. 

[JamesTedrick]

Hi Lynn,

While attachments are stored as related records from a geodatabase perspective, they are not accessed using the normal related records interface.  Instead, they can be accessed through the parent feature's pop-up or parent feature's table record.  See Pop-ups—ArcGIS Pro | ArcGIS Desktop and Edit file attachments—ArcGIS Pro | ArcGIS Desktop .