Last week, we released a patches to the Answers Search UI (v1.8.6 and v1.9.2) that a corrected an issue preventing sessions from being persisted. If you were using version 1.8 or 1.9 ahead of these patch releases, each search would start a new session. This fix makes it such that subsequent searches are associated with the same session.
If you are pinned to a patch for either 1.8 or 1.9, we recommend upgrading to this most recent patch.