What's the error message accompanying the skipped status?
The primaryAttributeValue shouldn't be the API name of the CA (or rather, there's no need for it to be).
Also, are you paying attention to daily API rate limits with your approach?
We're not getting an error message back.
So the primaryAttributeValue doesn't have to correlate to any of the activity fields. It can be a custom value
"primaryAttributeValue":"Logged into CMP",
Yes, we're paying attention to the API Rates, we don't have a huge audience for this application.
Is Lead ID 509 exist?
I tried "skipped" case.
When the lead is non-existent, "skipped" was returned
The other case
If the custom activity 100009 isn't approved or is wrong id, "skipped" is returned.
Verified the following.
The Lead exists with the correct Lead ID.
The Custom Activity is approved and the ID is accurate.
Any other ideas?