Jekyll build errors on Pages


When trying to generate a Pages site using Jekyll, I am getting a build error as below:

Liquid Exception: Liquid error (line 1): Invalid US-ASCII character “\xF0” on line 68 in assets/css/hydejack-9.1.6.css

I can see that it’s erroring on nested emoji within my scss file: content: "💡 TIP: ";

I have no idea why this would occur, the build works fine both locally, and via github pages using the exact same code base - any pointers would be much appreciated. I am sourcing code directly from a github repo