I am looping on a folder of output generated by the command "net localgroup administrators". Within the output is a list of security groups that belong to the local administrator group on a PC. My goal is to gather all security groups then create a matrix of PC names and these security groups. It would look something like this:

Here's what I have so far for code:

$Matrix = New-Object System.Collections.ArrayList

$Matrix | Add-Member -MemberType NoteProperty -Name "Asset" -Value "" -Force

$Files = Get-ChildItem -Recurse -Path "C:\PathToFiles\"

$Files | % {
    # Create a new object that'll get added to the Matrix arraylist.
    $Obj = New-Object System.Object
    
    $Obj | Add-Member -MemberType NoteProperty -Name "Asset" -Value ($_.Name).Split(' ')[0]

    # Get the name of the asset from the filename.
    # $Asset = ($_.Name).Split(' ')[0]

    $Extract = $false   
    $Lines = Get-Content -Path $_.FullName
    
    Foreach ($Line in $Lines) {
        If ($Extract -eq $false) {
            If ($Line -match "-{2,}") {
                $Extract = $true
            }
        }
        Elseif ($Line -eq "The command completed successfully.") {
            $Extract = $false
        }
        Else {
            $Obj | Add-Member -MemberType NoteProperty -Name $Line -Value "x"
        }        
    }
    $Matrix += $Obj
}
$Matrix | ft -AutoSize

I'm not sure if it's the way I'm creating the Matrix array or something else entirely but outputting $Matrix to the screen using format-table or exporting to CSV I'm missing several columns. Doing $Matrix[0] and $Matrix[1] shows me all the data I expect...

PS C:\Scripting> $Matrix[0] | ft

PS C:\Scripting> $Matrix[1] | ft

but

$Matrix | Export-CSV "C:\Temp\Output.csv" -NTI 

Only gives me the columns present in $Matrix[0].

What silly mistake am I making? Why can't I get an output with all my columns?