Found the answer for this one?
I got same issue
Hi Ramus,
The Lead is Created trigger will only apply to known leads, not anonymous leads. The lead will become known when the lead fills out a form or enters to Marketo thru your CRM or List import or API.
Hi Ashley
What if they are created through Rest API?
If you meant creating anonymous leads via the API, then you can't do that. Though leads created via the API will trigger the Lead is Created trigger.
Ok, its very strange i cant make it work then