Genesys Analytics API: Cursor pagination not working for conversation details

I’m trying to paginate through /api/v2/analytics/conversations/details/query using the Python SDK. The docs mention a nextPageToken, but setting page_token in the QueryConversationDetailsRequest just returns an empty list or the same first page. Here’s the snippet:

req = QueryConversationDetailsRequest(
 page_token=next_page_token,
 query=my_query
)
response = analytics_api.post_analytics_conversations_details_query(body=req)

Am I missing a specific header or is cursor-based pagination broken for this endpoint?