Seems to be the RapidWeaver's consolidated.css file adding this:
figure {
margin: 1em 40px;
}
Solution is to:
Add CSS) add this to your CSS in RapidWeaver:
figure {
margin: 0;
}
In a future update we'll change the Redactor setting to stop doing this. It's useful if people want to add captions to images but it is causing problems for some themes: