One button colour not changing

I have set my theme to "Lightest 1" throughout my site and customised my button colours within this theme. The button colour has changed everywhere except for the "send" button in my contact form. For some reason this is still white with black text (inverted for hover state).

I have checked the section and it is set to the right theme - I cannot figure out why it's not changing!

Does anyone have a fix for this that doesn't involve CSS?

Using Squarespace 7.1 and Fluid Engine.

Thank you

Hey bud,
When you click on the editor and then click on colours. Then select the colour theme you have chosen for the section that the button is in. Once you have done that click on the button and it should just show that buttons colours in the editing panel. Then you should be able to choose the right colour or the background etc. See my screenshot below. Let me know if this helps.