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Orchard 1.8: Form Submitted Activity Doesn't Work When Selecting Custom Form
In Orchard 1.8, the "Form Submitted" Activity does not work when you select a specific Custom Form. It only works when you select "Any".
I didn't test it with Custom Form Widgets, just Custom Form Pages.
I worked around it using Content Created/Updated activities since the specific content types used by the forms are ever only created via the forms.