JSM Incidents API from Forge app not authenticating

I’m trying to access the JSM Incidents API (https://developer.atlassian.com/cloud/incidents/rest/api-group-incident/#api-jsm-incidents-cloudid-cloudid-v1-incident-issueid-get) from a Forge app, but whichever endpoint I try I’m getting a 401.

I have the following scopes in my manifest:
- read:incident:jira-service-management
- write:incident:jira-service-management

Example API call:

const requestUrl = route`/jsm/incidents/cloudId/${cloudId}/v1/incident/${issueId}`;
let response = await api.asApp().requestJira(requestUrl, {
    method: "GET",
    headers: {
        "Content-Type": "application/json"
    }
});

Following the 401, my tunnel crashes out, has anyone else successfully used this API?

If I try with basic auth and a PAT token using the site URL I get a 403 instead of a 401 but it still kills the tunnel (no other error causes this issue with the tunnel… Using node 20.18.2