Analytics details query pagination: cursor vs page?

Trying to pull full conversation details via /api/v2/analytics/conversations/details/query. The docs mention a cursor parameter for pagination but the response JSON only gives me a page number and size. I’m looping through pages but hitting a wall after 20k records. Is the cursor field even returned in the response payload? Here’s my current request body:

{"size": 1000, "query": "["status:completed"]"}

Nothing in the response helps me jump to the next batch without re-fetching everything. Am I missing a header?