The ArcGIS Survey123 field app cannot load the dynamic choices using the search appearance from a feature service hosted in a different web GIS platform (ArcGIS Online vs. Enterprise) than where the survey is published to.

Workaround

Use the following workarounds to resolve this issue: 

• Use the ArcGIS Survey123 web app instead of the ArcGIS Survey123 field app.
• Share the survey publicly (if possible) and access the survey as an anonymous user.
• If sharing the survey publicly is not required and collecting the data through the ArcGIS Survey123 field app is needed, sign in, download the survey, sign out, collect data, sign back in and send your edits.
• Export the feature service and publish it to the same web GIS platform (ArcGIS Online vs. Enterprise) as the survey and use it as the search source for the dynamic choice list. 
• Make the original service private (or create a private view layer from the service), add it as an item to Portal for ArcGIS/ArcGIS Online using the service URL and store credentials. Reference this item as the search source for your dynamic choice list. 

Steps to Reproduce