WaitUntilReady against buckets failing on <6.5 clusters

There are consistent failures across the WaitUntilReadyTests for the tests running against 6.0 and 5.5 (also 7.0 - refer to comment), specifically these tests:

• handlesCreatingBucketDuringWaitUntilReady
• waitsForNewlyCreatedBucket

The waitsForNewlyCreatedBucket test has the following error, on a drop bucket call:
com.couchbase.client.core.error.FeatureNotAvailableException: The cluster does not support cluster-level queries (only Couchbase Server 6.5 and later) and no bucket is open. If an older Couchbase Server version is used, at least one bucket needs to be opened to dispatch this mgmt request!

And the handlesCreatingBucketDuringWaitUntilReady test times out, with retry reasons: BUCKET_OPEN_IN_PROGRESS.

My understanding is that the waitUntilReady should work against buckets only for <6.5 servers - at least, that is the behaviour in Gocb. So these tests should work.