This issue is now resolved.
We are still working on this issue.
Note: Seems like the email notification was not sent yesterday when the incident was created from the status service provider we use.
We are aware of the issue where a query that takes more than 60 seconds to process is not responding with a GUID to try later after 3 mins.
Currently, it's returning 504 gateway error code. It only happens if you request a large number of data that takes more than 60 seconds to process and return back to you.
We are looking into it and apologise for any inconveniences caused by this issue.
For queries that take less than 60 seconds (covers most of the calls) are not affected by this issue.
Reckon API Team