Hi Cameron, thanks for the quick response.
My bad, I copy’ed my last post’s workflow without further explanation. The one that is failing is the last one on bottom right. The token is going thru the header but I corrected that because I was showing my keys in my last post. I created a new custom credential in order to hide that.
Did you have any luck trying to accomplish this in the past? Comments endpoint work like a charm, but I tried several hours with the messaging endpoint with no luck. The rest of the flow works fine, that one node has clearly bad configuration… Hope I learn a big lesson while fixing this one haha
Is there anything else I coud share with you in order to get this up and working? 
Thanks again!
Juan