We use API forms in order to send form submissions from our main site and we use a program to send out lead alerts based on "Lead is Created" and "Source Type" is "Web Service API" (see screenshot below).
However, I am struggling to figure out how to track subsequent API form submissions. After the lead is initially created, the alert is no longer triggered. Since API submissions appear not to count as a "Fills Out Form", I can't figure out how to trigger a flow for API submissions beyond the initial one.
Add a unique value to the service invocation, trigger on the Change Data Value
However, I strongly advise against using API calls for this as it is almost never necessary, does not log Filled Out Form activities, and creates a DoS vulnerability.