Hi Chris,
This is (also) not working in the Community Events solution. I am using Survey123 Connect to modify a form created from the Community Event feature layer.
However, if I try to add a file or image field and add data to it, I receive the following error: "Uploads Capability is not supported for this service - cannot add attachment".
I have attachments enabled in the Community Events Layer and in settings, Add, update, and delete features is enabled.
Update!
As mentioned in this post, sync for the Feature Layer must be enabled in settings and then I can upload.