Confluence API: GET /content with extensions throwing a 404

The following request: GET

Is occasionally throwing 404 errors of the type :

{"statusCode":404,"data":{"authorized":false,"valid":false,"errors":[{"message":{"translation":"No content with id <ContentId{id=xxx}> can be found","args":[]}}],"successful":false},"message":"com.atlassian.confluence.api.service.exceptions.NotFoundException: No content with id <ContentId{id=xxx}> can be found"}

I am guessing this is a bug, which is due to the expansions containing entity ids which are not properly resolved server-side. Has anoyne experienced this ? Is there a workaround ?

After further investigation, removing the ancestor expansions stops the 404 for happening. 99% percent sure this is a bug on Atlassian side. What is the process to report ?