Task worklog not available via API after update to 11.1.0 Build 11128

After updating from build 11116 to 11128 v3 API calls to task worklogs are generating an error on Technician Field.

Error JSON

{"response_status":{"status_code":4000,"messages":[{"status_code":4001,"field":"TECHNICIAN_KEY","type":"failed","message":"Unknown error occurred while processing your request."}],"status":"failed"}}

Sanitised API URI

https://SDURI/api/v3/requests/47935/tasks/107646/worklog?TECHNICIAN_KEY=tkey

SDURI and tkey are obviously populated correctly with our instance and API key.

Removing worklog/ (https://SDURI/api/v3/requests/47935/tasks/107646?TECHNICIAN_KEY=tkey) from the string allows us to get the task details correctly

{"response_status":{"messages":[{"type":"success","message":"Task details fetched successfully","status_code":"200"}],"status":"success"}}

Removing the ?TECHNICIAN_KEY=tkey and

pasting string (https://SDURI/api/v3/requests/47935/tasks/107646/worklog) into browser correctly gets worklog details.

{"response_status":{"messages":[{"type":"success","message":"List view fetched successfully","status_code":"200"}],"status":"success"},"list_info":{"has_more_rows":false,"start_index":"0","end_index":"0","get_total_count":false,"row_count":"0"},"worklog":[]}

The same issue occurs for tasks with and without worklogs and under any technician key. API key has even been regenerated after update without resolving issue.