diff --git a/LiamNtfs/C4IT.LIAM.Ntfs.cs b/LiamNtfs/C4IT.LIAM.Ntfs.cs
index b60e3e7..8bf5fcd 100644
--- a/LiamNtfs/C4IT.LIAM.Ntfs.cs
+++ b/LiamNtfs/C4IT.LIAM.Ntfs.cs
@@ -467,10 +467,18 @@ namespace C4IT.LIAM
 
         private string GetRequiredCustomTag(string key)
         {
-            if (!CustomTags.TryGetValue(key, out var value))
-                throw new InvalidOperationException($"Missing NTFS custom tag '{key}'.");
+            if (CustomTags.TryGetValue(key, out var value) && !string.IsNullOrWhiteSpace(value))
+                return value;
+
+            if (string.Equals(key, "Filesystem_GroupPrefixTag", StringComparison.OrdinalIgnoreCase)
+                && CustomTags.TryGetValue("ADGroupPrefix", out value)
+                && !string.IsNullOrWhiteSpace(value))
+            {
+                return value;
+            }
+
+            throw new InvalidOperationException($"Missing NTFS custom tag '{key}'.");
 
-            return value;
         }
 
 
diff --git a/LiamWorkflowDiagnostics/MainWindow.xaml.cs b/LiamWorkflowDiagnostics/MainWindow.xaml.cs
index 00c2896..bb0a90a 100644
--- a/LiamWorkflowDiagnostics/MainWindow.xaml.cs
+++ b/LiamWorkflowDiagnostics/MainWindow.xaml.cs
@@ -35,7 +35,8 @@ namespace LiamWorkflowDiagnostics
         private ProviderTestSession _session;
         private bool _isInitializingUi;
         private readonly object _diagnosticsLogSync = new object();
-        private string _diagnosticsLogPath;
+        private string _diagnosticsGuiLogPath;
+        private string _diagnosticsStandardLogPath;
         private readonly string _settingsPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "LiamWorkflowDiagnostics.settings.json");
 
         public MainWindow()
@@ -67,10 +68,12 @@ namespace LiamWorkflowDiagnostics
                 var baseDir = AppDomain.CurrentDomain.BaseDirectory;
                 var logDirectory = Path.Combine(baseDir, "logs");
                 Directory.CreateDirectory(logDirectory);
-                _diagnosticsLogPath = Path.Combine(logDirectory, "LiamWorkflowDiagnostics.log");
-                cLogManagerFile.CreateInstance(_diagnosticsLogPath);
+                _diagnosticsStandardLogPath = Path.Combine(logDirectory, "LiamWorkflowDiagnostics.log");
+                _diagnosticsGuiLogPath = Path.Combine(logDirectory, "LiamWorkflowDiagnostics.gui.log");
+                cLogManagerFile.CreateInstance(_diagnosticsStandardLogPath);
                 cLogManager.Instance.Level = LogLevels.Debug;
-                AppendLog($"Logdatei: {_diagnosticsLogPath} (Level: Debug)");
+                AppendLog($"GUI-Logdatei: {_diagnosticsGuiLogPath}");
+                AppendLog($"Standard-Logdatei: {_diagnosticsStandardLogPath} (Level: Debug)");
             }
             catch (Exception ex)
             {
@@ -140,12 +143,12 @@ namespace LiamWorkflowDiagnostics
 
             try
             {
-                if (!string.IsNullOrWhiteSpace(_diagnosticsLogPath))
+                if (!string.IsNullOrWhiteSpace(_diagnosticsGuiLogPath))
                 {
                     var fileLine = $"{DateTime.Now:yyyy-MM-dd HH:mm:ss.fff} [{level}] {message}{Environment.NewLine}";
                     lock (_diagnosticsLogSync)
                     {
-                        File.AppendAllText(_diagnosticsLogPath, fileLine, Encoding.UTF8);
+                        File.AppendAllText(_diagnosticsGuiLogPath, fileLine, Encoding.UTF8);
                     }
                 }
             }