Hi!
Can you please check and let us know if you are still experiencing the problem?
We have a task https://phabricator.wikimedia.org/T202764 which I suspect describes the same issue. It is still open, and even though WDQS is running on Kafka in production and thus is not affected by it, I see it every time I run it on Labs (where Kafka stream is not available). So I think the issues with RC API on wikidata are still alive.
There's also a parallel issue of https://phabricator.wikimedia.org/T207718 with RDF fetching, which also still happens.