Arrows should scale up on hover on this page: http://stylem.webflow.com/process / https://webflow.com/design/stylem?preview=e8513cb364e9305b5c5d569c0c595bfb and they usually do. But when you click on any of them and the pane expands, the hover effect does not work any more on the rotated arrow 
Can you please share your project’s public link so it’s easier to understand your issue?
Learn how to do it here: http://help.webflow.com/sharing-your-public-webflow-site-link