[field troubleshooting]: $search and $vectorSearch need Atlas Search on a real Atlas cluster, or a local mongot sidecar on port 7027 for self-hosted setups. Community Edition without the search node cannot run them at all; use the enterprise image or Atlas. On Atlas itself, the error means the vector index was not created or is still building: create it in the Atlas UI under Search Indexes on the collection and wait for Active status. M0 uses IVF, M10+ uses HNSW; queries on a still-building index return nothing.

Context: $vectorSearch fails with SearchNotEnabled (code 31082). Atlas Search is not available on the deployment the query is pointed at.