Hello Aaron,
A hosted layer view should inherit the attachment setting of the original hosted feature layer by default. I am not aware of if having a join on the layer affects this or not, at this time.
- Can you reproduce the issue with viewing attachments on the View, if you create the hosted feature layer view without the join applied?
Another setting that will be worthwhile to check is to make sure that "hide attachments" is not enabled on newly created hosted feature layer View. Check this with the following steps:
- Open the item details page for the View layer that was created from the original layer.
- Look for the Layers list on the "Overview" tab.
- Click any "Show attachments" links that you see.
More information on showing and hiding attachments in Feature Layer Views can be found below.
AGOL: Manage Hosted Feature Layers (Specific Section link)
https://doc.arcgis.com/en/arcgis-online/manage-data/manage-hosted-feature-layers.htm#ESRI_SECTION2_7...
Regards,
TB