Basically there is a forecast detail record, with item/location/quantity, this search sums up all the quantities and takes the average. Heres an example searchDef that would log.

let searchDef = {
   type: "customrecord_rp_forecast_detail",
   filters: [
      [
         "custrecord_rp_fd_forecast",
         "anyof",
         "1"
      ],
      "AND",
      [
         "custrecord_rp_fd_item",
         "anyof",
         [
            "2827"
         ]
      ],
      "AND",
      [
         "custrecord_rp_fd_location",
         "anyof",
         [
            "3"
         ]
      ],
      "AND",
      [
         "custrecord_rp_fd_week_beginning",
         "within",
         "7/10/2021",
         "10/7/2021"
      ]
   ],
   columns: [
      {
         name: "custrecord_rp_fd_item",
         join: null,
         summary: "GROUP",
         label: null,
         type: null,
         function: null,
         formula: null,
         sortdir: "NONE",
         whenorderedby: null,
         whenorderedbyjoin: null,
         whenorderedbyalias: null
      },
      {
         name: "custrecord_rp_fd_location",
         join: null,
         summary: "GROUP",
         label: null,
         type: null,
         function: null,
         formula: null,
         sortdir: "NONE",
         whenorderedby: null,
         whenorderedbyjoin: null,
         whenorderedbyalias: null
      },
      {
         name: "formulanumeric",
         join: null,
         summary: "SUM",
         label: null,
         type: null,
         function: null,
         formula: "{custrecord_rp_fd_demand}/90",
         sortdir: "NONE",
         whenorderedby: null,
         whenorderedbyjoin: null,
         whenorderedbyalias: null
      }
   ],
   title: "Forecasted Demand"
}

If I run with

run()

it gives me a single result as expected

search.create(searchDef).run().getRange(0,1000)[0].getAllValues();
{GROUP(custrecord_rp_fd_item): Array(1), GROUP(custrecord_rp_fd_location): Array(1), SUM(formulanumeric): ".777777777777777777777777777777777777778"}

If I run with

runPaged()

it gives me nothing

search.create(searchDef).runPaged({pageSize: 1000}).fetch({index: 0}).data
[]

I also noticed if I take the date criteria out of the search, both

run()

and

runPaged()

give me the same expected result. I assume I have stumbled onto some weird NS bug with dates in criteria.

I expect that Shawn/Stalbert would say to use NFT which has momentJS to deal with dates