Right so this is the kind of thing I've been documenting for years and people still write it off as foxes or tree branches. Dogs don't stare at ceilings for foxes. They just don't.
What's the roof material, out of curiosity? Slate, tile, felt? And was the movement rhythmic or more irregular, like something stopping and starting? That detail matters more than people realise.
I had something similar in 2019, Derbyshire farmhouse, my lurcher wouldn't move from one spot in the hallway for three days. Not three hours. Three days. Something was absolutely present in that building and she knew it long before I started paying attention.
The dog is your best instrument here, genuinely. Note the direction its staring. Note the time. Get yourself a decent audio recorder running overnight if you can, not just your mobile, an actual dedicated recorder picks up frequencies your phone misses.
What part of the country are you in? That actually matters for what we might be dealing with.