Is your feature request related to a problem? Please describe.
With 'DASHBOARD_RBAC' ff on, when I don’t assign any role in dashboard props but the role has access to required dataset, still I get this error You don't have access to this dashboard.
Describe the solution you'd like
As the documentation mentions here, the fallback to dataset permission should work with ff enabled.
Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.
Additional context
I confirmed the same behavior in 1.3.2.
https://apache-superset.slack.com/archives/C01B6H6U8S2/p1625000708004100