add_FileTransferProgress crashes file transfer with Timeout error message for WinSCP (Powershell)

Question

I have an script that simply download all the files from given ftp server (backup tool).

Everything works fine but it takes hours before complete so I've decided to add some progress info based on WinSCP documentation:

function FileTransferProgress {
    param($e)
    if(($script:lastFileName -ne $Null) -and ($script:lastFileName -ne $e.FileName)) {
        Write-Host
    }
    Write-Host -NoNewline ("`r`t{0} ({1:P0})" -f $e.FileName, $e.FileProgress)
    $script:lastFileName = $e.FileName
}
$script:lastFileName = $Null


$sessionOptions = New-Object WinSCP.SessionOptions -Property @{
    Protocol = [WinSCP.Protocol]::ftp
    HostName = $ftpHostName
    UserName = $ftpUserName
    Password = $ftpPassword
}
...
$session.add_FileTransferProgress( { FileTransferProgress($_) } )
...
//start FTP session, open connection etc.
...

$transferOptions = New-Object WinSCP.TransferOptions
$transferOptions.TransferMode = [WinSCP.TransferMode]::Binary   
$session.GetFiles($hostFolderPath, ($targetFolderPath + "\*"), $False, $transferOptions).Check()

//message about finished trasnfer
...

Without my $session.add_FileTransferProgress( { FileTransferProgress($_) } ) everything works fine but it takes a long time to see the finish message. With add_FileTransferProgress I don't get any files transfered and instead, after few minutes I always end up with:

Error: Timeout waiting for WinSCP to respond

I've not changed anything else in the working code (only added FileTransferProgress and functin FileTransferProgress). I guess that program crashes when normally WinSCP would show "calculating directories" (before transfering files).

When I comment out $session.add_FileTransferProgress( { FileTransferProgress($_) } ) everything works fine. Also, uploading of few files with $session.PutFiles works both with commented and un-commented line (it outputs the % progress for upload).

---

As Martin Prikryl requested:

I run this script from Start -> Powershell (as administrator) and then cd to where it is placed and ./script.ps1 (exactly the same way for both cases).

I've placed:

$session.SessionLogPath = "I:\Sites\Temp\TransferLog.xml"
$session.DebugLogPath = "I:\Sites\Temp\TransferDebugLog.xml"

before $session.open(...) but only the debug log (TransferDebugLog.xml) appeared (I post parts of it, because it's huge file):

Executing Assembly: WinSCPnet, Version=1.3.5.6958, Culture=neutral, PublicKeyToken=...; Path: I:\Sites\WinSCP-5.9.2-Automation\WinSCPnet.dll; Location: I:\Sites\WinSCP-5.9.2-Automation\WinSCPnet.dll; Product: 5.9.2.0
Entry Assembly: 
Operating system: Microsoft Windows NT 10.0.14393.0
User: PolGraphic@...; Interactive: True
Runtime: 4.0.30319.42000
Console encoding: Input: Central European (DOS) (852); Output: Central European (DOS) (852)
Working directory: C:\Users\PolGraphic
Session.Open entering
...
Command: [open "ftp://...:***@... -passive=1 -timeout=15]
ExeSessionProcess.ExecuteCommand entering
ExeSessionProcess.ExecuteCommand leaving
ExeSessionProcess.ProcessEvent entering
  ExeSessionProcess.ProcessInitEvent entering
  ExeSessionProcess.ProcessInitEvent leaving
ExeSessionProcess.ProcessEvent leaving
ExeSessionProcess.ProcessEvent entering
  ExeSessionProcess.ProcessTitleEvent entering
    Not-supported title event [WinSCP]
  ExeSessionProcess.ProcessTitleEvent leaving
...
ExeSessionProcess.ProcessEvent entering
  ExeSessionProcess.ProcessInputEvent entering
    Scheduling output: [winscp> open "ftp://polgraphic...@..." -passive=1 -timeout=15]
  ExeSessionProcess.ProcessInputEvent leaving
ExeSessionProcess.ProcessEvent leaving
...
SessionLogReader.Read entering
  Opening log without write sharing
  Opening log with write sharing
  Log opened
  Skipping 0 nodes
  Read node 1: XmlDeclaration xml=version="1.0" encoding="UTF-8"
...

  SessionLogReader.Read entering
    Read node 21: Element group
    Log contents has not changed
  SessionLogReader.Read leaving
  Session.GetFiles entering
  Session.GetFiles leaving
  SessionLogReader.Read entering
    Waiting for log update and dispatching events for 50
    Waiting for log update and dispatching events for 100
    Waiting for log update and dispatching events for 200
    Waiting for log update and dispatching events for 400
    Waiting for log update and dispatching events for 800
... //lots of "waiting for log update"
    Waiting for log update and dispatching events for 800
    Waiting for log update and dispatching events for 800
  SessionLogReader.Read leaving
  ProgressHandler.Dispose entering
    Session.DisableProgressHandling entering
    Session.DisableProgressHandling leaving
  ProgressHandler.Dispose leaving
  ElementLogReader.Dispose entering
    ElementLogReader.ReadToEnd entering
      SessionLogReader.Read entering
        Waiting for log update and dispatching events for 50
      SessionLogReader.Read leaving
    ElementLogReader.ReadToEnd leaving
    Swallowing exception
  ElementLogReader.Dispose leaving
Session.GetFiles leaving
Session.Dispose entering
  Session.Cleanup entering
    Terminating process
    Command: [exit]