This affects 1.14.0-beta.2, which is not listed in the dropdown.

If we're searching the m101 cluster in 100YWeatherSmall.data for

{
  ts: ISODate("1984-01-01T00:00:00Z")
}

that will return 584 documents. But if we try to use the same query in a $match stage in the Aggregation pipeline builder, the builder won't let us preview the data because

> Expected "[" or AggregationStage but "{" found.

Both query & aggregation work in the mongo shell.

There don't appear to be any relevant messages in the browser console. Please let us know if you need any more information to debug this.