Survey123 submission "Getting service information" stuck reading related table

[GeospatialManagement]

I have a featureclass (checkpoints) which has its geometry defined in Workforce, and is populated using Survey123. The featureclass also has a related table that will use Survey123 to populated records (log of vehicles at checkpoints). 

When I try to submit a completed survey, either on the featureclass or related record I encounter an issue when "Getting service information" on the related record, which halts progress.

Is this a known issue, and does it have a fix?

Thank you.

[JamesTedrick]

Hi Doug,

Yes, you do not need attachment tables in the list of tables in the feature service; adding/editing/access to attachments are managed automatically.  I would suspect that it might be causing an issue in terms of reading the relationships in the service.

[DougBrowning]

Confirmed now that adding the _ATTACH tables was the problem.