Embedding a Quicksight QSearchBar for a user in a namespace (other than default)

I am able to successfully embed Quicksight dashboards using the multitenancy (namespaces-based) approach described in Quicksight's documentation. However, when I try to embed a Q Search Bar, the request completes successfully, but it generates a blank iFrame. Are Q Search Bars only allowed to be embedded for users in the default namespace? If not, how can I go about granting access to Q Topics to users in different namespaces and successfully embedding the Q Search Bar?

Here are some additional details:

I've followed the Amazon Quicksight documentation for embedding dashboards for registered users as well as embedding the Q search bar for registered users. I've created a workflow that creates namespaces and uses row level security to restrict access based on namespaces / groups. While the dashboard embedding works fine for users created in their respective namespaces, the Q Search Bar embedding does not.

This applies even if I create a Q Topic from the same dashboard that I can embed successfully for the namespace user. In both cases, the result is simply a blank iframe where the Q Search Bar should appear. The actual call to GenerateEmbedUrlForRegisteredUser does not throw an error when attempting to embed the Q Search Bar for a user from the namespace - the returned link just generates a blank iFrame.

However, if I use same operation ( GenerateEmbedUrlForRegisteredUser) using the OWNER account in the default namespace, the embedded Q Search Bar works fine. This appears to suggest that there is some sort of permissions issue at play. I cannot find any documentation that covers how to use the API to grant access to a Q Topic to a user in a specific namespace. I've tried removing RLS as well, but the iFrame is still empty. Any help would be greatly appreciated.