Hi @dbblackdiamond -
I know how frustrating this can be, but alas… there is a simple answer to your problem 
You were/are getting a 400 error response code because the webhook setup as indicated in the help center article is meant to work while testing with a working Particle device, not with the test button option in the Particle console. As you can see in the URL, they advise to use the {{{PARTICLE_DEVICE_ID}}} key which means that every webhook call will replace that particular portion of the URL with the corresponding device id triggering the webhook.
This means your web hook is probably functioning just fine, I suggest testing it with a complete setup of a connected Particle device and monitor the inflow of data to your Ubidots account. You can refer to aprevious project of mine, I posted the working code there connecting to Ubidots dashboard.
Hope this helps