I have a federated ArcGIS Enterprise setup, but I want to use a feature service for Survey123 with ArcGIS Online rather than my Portal. This should be the same process as using a non-federated service I would have thought.
I have created a secure feature service and registered this with ArcGIS Online and stored my credentials. I have then re-uploaded my survey with this service referenced in my form_id and submission_url. This all goes through fine with no errors raised. I can then download the survey fine to my device. When I submit my completed survey all of the data goes through fine, but the attachment raised a 'Code 400 - User does not have privileges to perform this operation.' error.
I also cannot add an attachment from within ArcGIS Online to this feature service when editing in a web map even though I can edit the rest of the data. I can also edit the related table that the repeat uses no problem even though this presumably is the same relationship/related table setup as an attachment uses. Is there any way of resolving this issue?