Zoho Creator API json format not working? xml OK

Zoho Creator API json format not working? xml OK

https://creator.zoho.com/api/json/student-record/view/Invoice_Extraction_Report?scope=creatorapi&authtoken=mytoken&zc_ownername=ricwilson

returns a 500 error

but

https://creator.zoho.com/api/xml/student-record/view/Invoice_Extraction_Report?scope=creatorapi&authtoken=mytoken&zc_ownername=ricwilson

works.

This was all fine a few days ago. Please advise if this is a current issue.

Rewriting interfacing to process xml instead of json is not an option.