GAH!!! Mouse Drivers - turn out I am on 3.1.1 and the latest is 3.1.4 - will let you know if the update changes the behaviour.

If it does - feeling like a chump aside - shouldn’t this be high on ‘check this’ help pages?

And shouldn’t it be easier than having to find a lightening to USBC adapter - so i can plug the mouse into the computer?