@aws-solutions-constructs/aws-sns-sqs not honoring existingTopicObj or existingQueueObj

When I use @aws-solutions-constructs/aws-sns-sqs, the construct creates its own topic and queue, and makes the subscription between them, regardless of whether I specify existingTopicObj and/or existingQueueObj. E.g.,

// subscribe the queue to the ihsTopic (from the global stack)
const snsToSqsStack = new SnsToSqs(this, env.buildId(baseStackName, 'SnsToSqsPattern'), {
    existingTopicObj: ihsTopic
});

results in the creation of

   dev2-MPNManagementIHSStack-dev2MPNManagementIHSSnsToSqsPatternSnsTopic3CE13A35-dK7u7eSgJnJ6
   subscription: 72965362-92af-4ee3-8fb4-398e90ed93dd	arn:aws:sqs:us-west-1:225996342467:dev2-MPN...

rather than using the specified

   dev2-MPNManagementGlobalIHSTopic

I understand that this is still in 'experimental' status, so should I not expect this feature to work?

Please advise, thank, Mitchell