HTTP 500 Error for some WFM Reports

Hi,

We're using the WFM Public API (EAP) to fetch report data via the GET /wfm/public/api/v1/reports/{templateId}/data endpoint. Two of our three report templates consistently return HTTP 500 (Server Error), while the third works perfectly with the same authentication, parameters, and request format. What we observe:

Report template A: returns HTTP 200 with valid JSON — works as expected

Report template B: returns HTTP 500 with an HTML "Server Error" page

Report template C: returns HTTP 500 with an HTML "Server Error" page

What we've verified:

All three requests use identical authentication (API token), URL structure, and query parameters — only the template ID differs

The response for failing templates has content-type: text/html instead of application/json, suggesting the error occurs at the server/proxy level before reaching the API logic

We tested with both full parameters (?startTime=...&endTime=...&perPage=100&page=1) and minimal parameters (?startTime=...&endTime=...) — both return 500 for the affected templates

Both failing reports are fully accessible and display data correctly in the WFM browser UI

All three templates were working via the Public API as recently as mid-February 2026, but the two started returning 500 errors sometime after that

Environment:

Authentication: Basic auth with API token (email/token format)

Endpoint: GET /wfm/public/api/v1/reports/{templateId}/data

The working and failing templates are on the same Zendesk account

Any guidance from the Zendesk team would be appreciated.