Yes. And this appears only sometimes, that's the problem. Sometimes it works, sometimes it doesn't. I feel like something might be out of or in focus. I am not sure yet.
@Andreas_Hegenberg - Reproduced it right now on theverge.com. The HUD triggered and the scroll didn't work, it kinda choked for a few milliseconds and just did a regular scroll! Logs here.
I can reproduce it, but can't see a reason why. It could be some change in how Safari handles simultaneous scroll & keyboard events.
However a simple workaround is to assign the predefined actions "Home (Beginning Of Page)" and "End (End of Page)" instead, Safari seems to handle these correctly always.