As it appears, I must open a project from the project file itself.
For context, I am using VEP7 on the local system but this is a most troubling situation as I believe this to be the last update to Cubase 10.
Saying that, I would happily upgrade to 10.5 but I’m not sure if the issue is fixed there (notwithstanding ongoing issues with XML archives) and can’t know because my Trial has expired (I have other keys but SB only seem to offer one trial per person NOT per key).
Cheers and hope this situation is resolved soon.