User filter-Records

Can you try this

a!localVariables(
  local!acctExecs: getdistinctusers(cons!ACCOUNT_OWNERS),
  local!mappedUsers: a!forEach(
    items: local!acctExecs,
    expression: a!map(
      username: fv!item,
      displayName: user(fv!item, "firstName") & " " & user(fv!item, "lastName")
    )
  ),
  local!sortedUsers: todatasubset(
    local!mappedUsers,
    a!pagingInfo(
      startIndex: 1,
      batchSize: -1,
      sort: a!sortInfo(field: "displayName", ascending: true)
    )
  ).data,
  a!recordFilterList(
    name: "Account Executives",
    options: a!forEach(
      items: local!sortedUsers,
      expression: a!recordFilterListOption(
        id: fv!index,
        name: fv!item.displayName,
        filter: a!queryFilter(
          field: recordType!Customer.fields.AccountOwner,
          operator: "=",
          value: fv!item.username
        )
      )
    )
  )
)

This is not working distinct user function

It says expression evaluation error at function user

 Stefan Helzle 

Can you share the error you are getting? 

You need to make some changes based on your actual code.
share your error here.

Im not getting error but the field is not sorting.
Im querying from case table all the assigned to and casdID,assigned to are in (username),I wanted to display the user's name in sorting order.I am using the user function to get the firstname and lastname ,If the its null make it as unassigned.
At wht place I can sort it

I cant share the code .Please help me

I have replaced recordtype with caseid and assigned to

Can someone help me with this issueShubham Aware 

Sort the mapped list with displayName field using todatasubset() before a!forEach creates recordFilterListOption() options.

local!mappedData: a!forEach(
  items: local!uniqueData,
  expression: a!map(
    values: fv!item.values,
    displayName: if(
      a!isNullOrEmpty(index(fv!item,"label","")),
      "Unassigned",
      if(index(fv!item,"label","")="System","System",
        user(index(fv!item,"label",""),"firstName") & " " &
        user(index(fv!item,"label",""),"lastName")
      )
    )
  )
),
local!sortedData: todatasubset(
  local!mappedData,
  a!pagingInfo(startIndex:1,batchSize:-1,sort:a!sortInfo(field:"displayName",ascending:true))
).data,