API - 403 calling /membership endpoint

We're using the same subscription key to call the RE NXT Sky API in two different environments. In Environment A, all API calls—including /membership endpoints—are working. In Environment B, /constituent endpoints work, but /membership endpoints return a 403 Forbidden error.

For example:

✅ This works:
https://api.sky.blackbaud.com/constituent/v1/constituents/4065/memberships

❌ This fails (403):
https://api.sky.blackbaud.com/membership/v1/memberships/77/membershipdetails?limit=5000

The user account generating the access token has full permissions to view and modify memberships in Environment B. The documentation suggests a 403 occurs when the user lacks permissions, but that's not the case here.

Our client application is also registered with full access to the environment, and the same subscription key works fine for membership endpoints in the other environment.

Is there an environment-specific setting required to enable access to the /membership API? Or anything else that might cause a 403 in just one environment?