API 2.0 not working: GET the activity for a pull request

https://confluence.atlassian.com/bitbucket/pullrequests-resource-423626332.html#pullrequestsResource-GETtheactivityforapullrequest

GET https://api.bitbucket.org/2.0/repositories/

{owner}

/

{repo_slug}

/pullrequests/

{pull_request_id}

/activity

This API currently gives the following error message for all our pull requests in all our repositories:
{"error": {"message": "Resource not found"}}

It was working previously.