I do have a note though, which I think came from some old Tasker documentation
"Tasker can only receive intents which are sent to broadcast receiver components, not to activities or services."
So you may have more luck with app.BroadcastIntent()
The action is the first argument so you can drop the first null.
I don't know how tasker deals with intents but if you really don't want any payload, that could be enough to test it.
That's what the original "Receive Intent" sample did before DS could even send intents, if I recall correctly.
Take a look in the samples that come with DroidScript.