Great to hear you managed the previous one.
As for the workflow rules, I took my own tests, but it seems the 'Parent' workflow rules DO run, (I particularly tested bulk REST API).
As you've sent detailed information and access to your account in the support ticket you've opened separately (you did a really good job on that!), I could look into the specifics in your account.
I think the workflow rules don't run because the conditions evaluate to false, meaning the Task data you've entered is the cause of the issue.
Specifically I could see the Forecast Task Type is not set. Could you look into the data sent with the API and the workflow rules again?
Hope this helps,