Right so something very similar happened to me about two years ago in our old house just outside Penrith. Footsteps on the roof, slow and deliberate, not like a cat or a bird, more like something with actual weight to it. And our old collie Bess just sat there staring upward with her hackles up, completely silent, which was honestly more unsettling than if she'd been barking.
Never figured out what it was. Checked the roof the next morning and there was nothing, no damage, no prints in the moss, nothing.
The dog reaction is the part that gets me every time with these stories. Animals don't perform. They either react or they don't and when they go that quiet and fixed like yours did, something has genuinely caught their attention. Whatever it is, it's real enough for them.
Has this happened more than once for you or just the one night?