Ok here's a clue, I just got this feedback on a related question from @samlittlefair.
It seems the correct way to connect things is like this.
In the prismic UI, name your slice with two words separated by a space aka "Share Print"
This will then automatically create the json code with snake case aka "share_print"
In your code name your Slice with PascalCase aka "SharePrint".
And everything should wire up.
I just updated my naming conventions for everything based on this and sadly it hasn't fixed the issue for me.
@samlittlefair could you shed some light?
@samlittlefair maybe you could help us out?