Update:
Upon further inspection, the reason for related tables not being pulled in was the relationships were 1:1.
Changed them to 1:Many and it works.
I'm having an issue with survey123 Connect pulling in related tables for my feature service. Anyone able to take a looksie?
I'm using Version 3.6.137 of Survey123 connect.
I have GlobalIDs on the feature class related to GUIDs on the related tables. The related tables are relationship classes that were published from ArcGIS Pro.