Just checking, you're using the NVC case number, not the USCIS one? I know it sounds daft but it's an easy mistake to make!
Your case status would have been updated all the time with things like 'At NVC', 'In Transit', 'Ready' etc, but if you're definitely putting the right details in then maybe it's just a glitch. Try another browser or just keep checking.
Good luck, and please do update your timeline now you've been interviewed, to pay it forward and help other EB1 applicants. Thanks.