Note: As always - I'll hang my head in shame if I'm wrong 😉
Super Admins should have access to everything - and in fact the documentation says they do ... but they don't.
I got this from support:
The users who have “Super-Role” role, have permission to do anything in Incorta, they can also see all resources even if it is not shared with them, this case apply to everything except the Dashboards. Even if you are a user with super-role permission, you can only access dashboards if and only if it is shared with you or your group, this is because dashboards might have sensitive data.
Obviously this is silly - a super admin can query any data a dashboard author can, so "sensitive data" is available either way. The only thing this restriction does is make it more difficult for a super admin to work on dashboards/insights w/out first having the owner make an exception to their sharing scheme.