Took me a week and a half to work this out and figured I’d post here to hopefully save someone else the pain.
I was having an issue when trying to load projects, where Cubase would just “hang” on the “Reading Project File” window.
Turned out it was Cubase IC. If I try to open a project with the IC app open on my iPad, it will not load. Simple solution is to close Cubase IC, and then the project will open. No problem to re-open Cubase IC once the project is loaded.