I've followed up to a comment version of this question in https://community.esri.com/groups/survey123/blog/2018/11/02/st-kilda-penguin-release-31?commentID=68... . This looks to be an issue with the index on the GlobalID field of the table.
I didn't want to start a new thread, since my issue is directly related to BUG-000117394, and I wasn't sure where I might receive an answer first. I already commented on the thread, for which you provided the link above, but I am going to outline my problem here as well. Any help is greatly appreciated :)
I still struggle with BUG-000117394 "The INSERT statement has conflicted with the FOREIGN KEY constraint" error (see attached screenshot).
I followed the following work flow:
I initially created the survey using Survey123 3.9, but I re-published using the latest version. Any ideas what I am doing wrong? One thing I am not entirely sure about is: I might have added the attribute index to the GlobalDs AFTER creating the relationship classes. would that matter at all?
Thanks a lot for the help.