can't see theme update until creating a post/page

We have a number of sites in a multi site environment. When I make updates to any of the themes that the sites use and then refresh the site in the browser, the change is not shown. It doesn’t matter if I clear my cache or not. The only thing that forces the change to show up is to go into an existing post and clicking the update button, or creating a new post/page. We have another multi site environment set up but there we don’t have this problem. Anyone know what causes this? Thanks.