Control Access to Objects challenge: Recruiting objects missing. Position, Candidate, Job Application, and Review are not in Object Manager. Created new Trailhead Playground but still missing objects. Challenge cannot complete.

I launched the challenge with my Trailhead Playground, but the Recruiting sample objects are not available. 

Missing objects: 

- Position 

- Candidate 

- Job Application 

- Review 

I checked Setup → Object Manager and searched, but they do not appear. 

I created a Permission Set "Manage Positions" and added it to the "Recruiters" Permission Set Group, but the challenge still fails because Position object is missing. 

Please help me get the correct org/sample objects enabled.