Did Hello World Add-on walkthrough video but button isn't showing?

I followed the steps in the "Hello World Add-on" walkthrough video https://servicem8.wistia.com/medias/wq8m85x2ib but the "Hello Action" button isn't showing on the Modify job window?

I checked that manifest 1.0 status is "Ready".

I got a "Function validated successfully" when I saved the code that I'd copied and pasted in from https://github.com/servicem8/addon-sdk-samples/tree/master/app-actions-addon-nodejs

I clicked on the "Private Add-on Install URL" and allowed it access.

My "Test" add-on is listed in our Add-ons and is turned on. I tried logging off and back into ServiceM8 but that didn't help either.

Any suggestions would be greatly appreciated.