Added new colors to theme.json but they're not being generated as classes

[LobsterDM]

I'm hoping someone can help me out here. I've created a range of colours within theme.json that are appearing as options in the admin area when I edit a block but they're not being generated into css classes when I use them in classes.

For example, I have a color called "Steelblue" that is showing as an option in block editor but when I try to use it as a text color using text-steelblue it's not being picked up.

Does anyone have any ideas?