I did setup a personalisation campaign with specific coverstories on our homepage against a control experiment. It works fine with desktop but with Smartphones there is an issue. When switching to landscape mode the personalized experience gets overwritten and the default pops up.
You can mimic the experience by doing this with your Smartphone:
Can you share the device details? I tried this on Android and on the desktop Chrome browser (using Dev Tools) and it worked as expected: Fernreisen was displayed and the default experience was not visible.