Sticky header breaks when adding logo – on clean install

Hi, I'm using Clean Fotografie (Free edition). The sticky header works perfect until I add a logo (Site Identity > logo). I tried deactivating plugins, but on a second thought I decided to make a local clean installation (Pure Wordpress and the Theme on my localhost) and the same behavior appears. It seems that the JS no longer toggles classes to [div.site-header-main] which remains with class .site-navigation-tall (instead of switching to the fixed one) I tried with two images, one 100x100px and one 55x55px… both break it. Any ideas on how to solve this? ThanksInAdvance!