When trying to add Salesforce UI Elements into Lightning Page or Flow - I am seeing this error when opening page or running the flow
Refused to frame 'https://mydomain--mysandbox-box.sandbox.vf.force.com/' because an ancestor violates the following Content Security Policy directives: "frame-ancestor 'self'"
Additional Info: https://developer.box.com/guides/tooling/salesforce-toolkit/ui-elements/