Custom Tooltips won't appear

Hey there,

I've followed the guide below to build a custom tooltip, with the intention of it appearing when I hover over a section in my column chart, but only the default tool tip is appearing. I've also got screenshots of the custom tool tip, vs what appears when hovering over a section of a column below. 

How do you make the custom tool tip actually appear on hover vs the default?

Thank you!

https://docs.microsoft.com/en-us/power-bi/create-reports/desktop-tooltips?tabs=powerbi-desktop