Issue in read only grid selection

Hi,
I've two interfaces, On selecting one row (Read only grid) then dependent interface(Read only grid) is displaying data based on the selection of rows.
The issue is when I'm selecting the grid rows one by one the total count is 27.

but when I select all rows quickly then the dependent interface count is reduced to 16.

here is the code snippet of dependent interface.

a!gridField(
  data: local!calculatedMetricList,
  initialSorts: {
    a!sortInfo(field: "adherence", ascending: true)
  },
  secondarySorts: {
    a!sortInfo(
      field: "employeeFullName",
      ascending: true
    )
  },
  pageSize: 20,
  borderStyle: "LIGHT",
  spacing: "DENSE",
  selectable: true,
  disableRowSelectionWhen: false,
  selectionValue: ri!selection,
  selectionStyle: "ROW_HIGHLIGHT",
  selectionSaveInto: {
    ri!selection,
    a!save(ri!selectedSupervisorRow, save!value),
    a!save(
      ri!selectedSupervisorHierarchy,
      if(
        length(fv!selectedRows) > 0,
        append(
          ri!selectedSupervisorHierarchy,
          cast(
            typeof(
              'type!{urn:com:appian:types:INO}INO_employeeHierarchyHelper'()
            ),
            fv!selectedRows[length(fv!selectedRows)].hierarchy
          )
        ),
        difference(
          ri!selectedSupervisorHierarchy,
          cast(
            typeof(
              'type!{urn:com:appian:types:INO}INO_employeeHierarchyHelper'()
            ),
            fv!deselectedRows[length(fv!deselectedRows)].hierarchy
          )
        )
      )
    ),
    a!save(ri!agentSelection, null),
    a!save(ri!selectedAgent, null)
  },
  columns: {}
)