Add-PWSavedSearch syntax for $FIELD$ search

According to the change log, support for $FIELD expression was added in PWPS_DAB version 2.1.18.0

using the following powershell code:

$AuditUser = 'thbn'
$SearchField = "`$FIELD(10)`$ = (SELECT DISTINCT o_userno FROM dms_user WHERE o_username in ('$AuditUser'))"
$AuditSkabelon = 'Innovationsprojekter\Test_THBN\'
$SearchFolder = 'Større anlæg\7x\'

Get-PWRichProjects -FolderPath $AuditSkabelon -JustOne | 
Add-PWSavedSearch -SearchName 'CAD-files' -Environment 'Dokument' -DocumentName $SearchField -SearchFolder $SearchFolder -SearchSubFolders -UpdatedAfter 10/10-2020 -ReplaceExisting -Verbose

Gives the following in the search builder:
='$FIELD(10)$ = (SELECT DISTINCT o_userno FROM dms_user WHERE o_username in ('thbn'))'

however, this was the expected search result:
$FIELD(10)$ = (SELECT DISTINCT o_userno FROM dms_user WHERE o_username in ('thbn'))

Do we have any examples for writing the $FIELD expression ?