Trying to call the URL: https://<JIRA_URL>/rest/greenhopper/1.0/rapid/charts/scopechangeburndownchart?rapidViewId=XXXX&sprintId=XXXX
Working perfectly when using basic authorization, but not with bearer (OAuth) authorization.
Cross-checked my OAuth credentials with another API:
https://<JIRA_URL>/rest/api/2/dashboard
Worked perfectly with both basic and bearer authorization.