@zeke-holloman a correction on my part, when I looked through the thingspeak API, both the historical and the MQTT method use the POST to deliver it to thingspeak, however they have a slightly different API.
Initially when looking at your posting I assumed you had removed the keys as it was public, however looking at your your trace it is saying that it doesn’t have the keys in it.
Your response is
Topic [ 41 ]: channels/thingSpeakChannelID/publish/thingSpeakChannelKey
and it should look something like
Topic [ 38 ]: channels/5940/publish/DHCKWX0HZQLXGIAX <–ThingSpeakPublisher
Please confirm that your run has the API keys in.
If that doesn’t work, can you post your platformio.ini
I’m committed to something for the next couple of hours but I can add describe the STREAMDEBUG setup after looking at your platformio.ini