Hello - we're trying to add a new custom field (checkbox) to an existing Online Customer form. We've created the field but when I add it to the Online Customer form in the UI, I get a popup saying

You have already submitted this form, would you like to submit it again?

If I choose Cancel, nothing happens. If I choose OK, I get this error:

You are missing the following required field(s):
NLCUSTENTITY_CHE_SL_REPORT_ADDON

I also tried a Save As but get the same popup and error. Any ideas? Thanks!