Setting a specific button colour on interaction when a background image is set - does not work

Now that we can add background images to blocks, it seems to have taken away the ability to specify the button colour.

It doesn't matter what button colour I choose, it's always either dark or light - but you still give me the option to set a colour.

This seems wrong. Either take away the button colour when using a background image, or allow us to set a button colour.