PowerShell Script uploading file to SharePoint doesn't work when run from Task Scheduler

Overview: I have a script which runs a query to extract all Audit Logs from the past day, from a SharePoint site. It then creates a .csv file, and uploads it to the "Shared Documents" folder on SharePoint. The script works perfectly when I manually run it from PowerShell console, regardless if it's run with admin rights, or not.

NOTE: This SharePoint solution is On-Premise, not Online.

The Issue: When I run the script from Task Scheduler it generates the .csv file, and completes the whole script, but the file is never uploaded. There's no error messages.

Task Scheduler Settings: I use "Run whether user is logged on or not" and "Run with highest privileges"

Here's the full script:

Start-Transcript -Path "C:\Timer Jobs\exampleDomain.Audit.CreateAndTrimLog\transcript17.txt" -NoClobber

Add-PSSnapin "Microsoft.SharePoint.PowerShell"

#Get date, and format it. Used for file name, and for deleting old Audit files
$today = Get-Date
$startDate = $today.AddDays(-1)
$todayFormatted = $today.ToString('dd-MM/yyyy_HH-mm-ss')

#Get site and save siteURL
$siteUrl = "https://example.com"
$docLibName = "Shared Documents"
#site is needed for Audit Query
$site = Get-SPSite -Identity $siteUrl
#web is needed to upload the file
$web = Get-SPWeb -Identity $siteUrl
$list = $web.Lists[$docLibName]
$folder = $list.RootFolder
$files = $folder.Files


#Creaty query for Audits
$wssQuery = New-Object -TypeName Microsoft.SharePoint.SPAuditQuery($site) 
$wssQuery.SetRangeStart($startDate)
$wssQuery.SetRangeEnd($today)

#Create Audit Collection object
$auditCol = $site.Audit.GetEntries($wssQuery)

#Get all users on site
$users = $site.RootWeb.SiteUsers

#Get and add $userName to each $audit
#Ignore when it says "User cannot be found" in log
$CachedUsers = @{};
foreach($audit in $auditCol){
    $curUserId = $audit.UserId;
    $user = $null;
    if($CachedUsers.$curUserId -eq $null){
        $user = $users.GetById($curUserId);
        $CachedUsers.$curUserUI = $user;
    } else {
        $user = $CachedUsers.$curUserId;
    }

    $userName = ($user.DisplayName + " <" + $user.LoginName) + ">";
    $audit | Add-Member NoteProperty -Name "UserName" -Value $userName -Force;
}

#Export CSV-file. Save fileName and filePath for when uploading to SharePoint
$fileName = ("domain_Audit_Log_" + $todayFormatted + ".csv")
$filePath = "C:\Users\xml\" + ($fileName)
$auditCol | Export-Csv -Append -path ($filePath) -NoTypeInformation -Delimiter ";" -Encoding UTF8


$file = Get-ChildItem $filePath
[Microsoft.SharePoint.SPFile]$spFile = $web.GetFile("/" + $folder.Url + "/" + $file.Name)


if($spFile.Exists -eq $false) {
    #Open FileStream
    $fileStream = ([System.IO.FileInfo] (Get-Item $file.FullName)).OpenRead()
    #Add File
    Write-Host "Uploading file" $file.Name "to" $folder.ServerRelativeUrl "..."
    try {
        [Microsoft.SharePoint.SPFile]$spFile = $files.Add($folder.Url + "/" + $file.Name, [System.IO.Stream]$fileStream, $true)
        Write-Host "Success"
    } catch {
        Write-Host "Error"
    }

    #Close FileStream
    $fileStream.Close()
}

$web.Dispose()
#$site.Audit.DeleteEntries($startDate)

Only difference in the Transcript.txt file, when I run it Manually vs. Task Scheduler is these lines, that are added in the Task Scheduler Tanscript:

PS>$global:?
True

The Transcript prints the "Success" line from my Try-Catch