validateAfter: "SUBMIT" is not working

Appian is evaluating validation before I submit, even though the parameter is set.

              a!validationMessage(
                message: "Field is Required",
                validateAfter: "SUBMIT",
                showWhen: a!isNullOrEmpty(
                  rule!BBP_process_CurrencySanitizer(a!defaultValue(ri!value, null))
                )
              )

Why is Appian behaving like that? It should be expecting my submit.