diff --git a/src/OutlookGoogleCalendarSync/Outlook/OutlookCalendar.cs b/src/OutlookGoogleCalendarSync/Outlook/OutlookCalendar.cs
index 7716985..13f02c3 100644
--- a/src/OutlookGoogleCalendarSync/Outlook/OutlookCalendar.cs
+++ b/src/OutlookGoogleCalendarSync/Outlook/OutlookCalendar.cs
@@ -63,7 +63,7 @@ public enum Service {
         public Outlook.EphemeralProperties EphemeralProperties = new EphemeralProperties();
 
         /// <summary>Outlook Appointment excluded through user config <Appt.EntryId, Event.Id></Appt.EntryId></summary>
-        public Dictionary<String, String> ExcludedByCategory { get; set; }
+        public Dictionary<String, String> ExcludedByCategory { get; private set; }
 
         public Calendar() {
             InstanceConnect = true;
@@ -144,6 +144,7 @@ public List<AppointmentItem> FilterCalendarEntries(SettingsStore.Calendar profil
 
             List<AppointmentItem> result = new List<AppointmentItem>();
             Items OutlookItems = null;
+            ExcludedByCategory = new();
 
             if (profile is null)
                 profile = Settings.Profile.InPlay();
diff --git a/src/OutlookGoogleCalendarSync/Sync/Calendar.cs b/src/OutlookGoogleCalendarSync/Sync/Calendar.cs
index f30d4b8..2a86f12 100644
--- a/src/OutlookGoogleCalendarSync/Sync/Calendar.cs
+++ b/src/OutlookGoogleCalendarSync/Sync/Calendar.cs
@@ -315,7 +315,6 @@ private SyncResult synchronize() {
 
                 List<AppointmentItem> outlookEntries = null;
                 List<Event> googleEntries = null;
-                Ogcs.Outlook.Calendar.Instance.ExcludedByCategory = new Dictionary<String, String>();
                 Ogcs.Google.Calendar.Instance.ExcludedByColour = new Dictionary<String, String>();
                 Ogcs.Google.Calendar.Instance.ExcludedByConfig = new List<String>();
                 if (!Ogcs.Google.Calendar.IsInstanceNull)