diff --git a/ts/background.ts b/ts/background.ts
index 7b36cc129b6..a46bc69620e 100644
--- a/ts/background.ts
+++ b/ts/background.ts
@@ -197,6 +197,7 @@ import { DataReader, DataWriter } from './sql/Client';
 import { restoreRemoteConfigFromStorage } from './RemoteConfig';
 import { getParametersForRedux, loadAll } from './services/allLoaders';
 import { checkFirstEnvelope } from './util/checkFirstEnvelope';
+import { BLOCKED_UUIDS_ID } from './textsecure/storage/Blocked';
 
 export function isOverHourIntoPast(timestamp: number): boolean {
   return isNumber(timestamp) && isOlderThan(timestamp, HOUR);
@@ -1360,6 +1361,18 @@ export async function startApp(): Promise<void> {
 
     initializeExpiringMessageService(singleProtoJobQueue);
 
+    log.info('Blocked uuids cleanup: starting...');
+    const blockedUuids = window.storage.get(BLOCKED_UUIDS_ID, []);
+    const blockedAcis = blockedUuids.filter(isAciString);
+    const diff = blockedUuids.length - blockedAcis.length;
+    if (diff > 0) {
+      log.warn(
+        `Blocked uuids cleanup: Found ${diff} non-ACIs in blocked list. Removing.`
+      );
+      await window.storage.put(BLOCKED_UUIDS_ID, blockedAcis);
+    }
+    log.info('Blocked uuids cleanup: complete');
+
     log.info('Expiration start timestamp cleanup: starting...');
     const messagesUnexpectedlyMissingExpirationStartTimestamp =
       await DataReader.getMessagesUnexpectedlyMissingExpirationStartTimestamp();
diff --git a/ts/models/conversations.ts b/ts/models/conversations.ts
index 2bde5b38d51..02f2a8a34b0 100644
--- a/ts/models/conversations.ts
+++ b/ts/models/conversations.ts
@@ -930,7 +930,7 @@ export class ConversationModel extends window.Backbone
     const wasBlocked = this.isBlocked();
 
     const serviceId = this.getServiceId();
-    if (serviceId) {
+    if (serviceId && isAciString(serviceId)) {
       drop(window.storage.blocked.addBlockedServiceId(serviceId));
       blocked = true;
     }
@@ -962,7 +962,7 @@ export class ConversationModel extends window.Backbone
     const wasBlocked = this.isBlocked();
 
     const serviceId = this.getServiceId();
-    if (serviceId) {
+    if (serviceId && isAciString(serviceId)) {
       drop(window.storage.blocked.removeBlockedServiceId(serviceId));
       unblocked = true;
     }
@@ -2344,6 +2344,10 @@ export class ConversationModel extends window.Backbone
       ourAci: window.textsecure.storage.user.getCheckedAci(),
       forceSave: true,
     });
+    if (!this.get('active_at')) {
+      this.set({ active_at: Date.now() });
+      await DataWriter.updateConversation(this.attributes);
+    }
     window.MessageCache.toMessageAttributes(message);
     this.trigger('newmessage', message);
     drop(this.updateLastMessage());
diff --git a/ts/textsecure/storage/Blocked.ts b/ts/textsecure/storage/Blocked.ts
index 181c5246ba9..e46d9d5f075 100644
--- a/ts/textsecure/storage/Blocked.ts
+++ b/ts/textsecure/storage/Blocked.ts
@@ -7,9 +7,9 @@ import type { StorageInterface } from '../../types/Storage.d';
 import type { ServiceIdString } from '../../types/ServiceId';
 import * as log from '../../logging/log';
 
-const BLOCKED_NUMBERS_ID = 'blocked';
-const BLOCKED_UUIDS_ID = 'blocked-uuids';
-const BLOCKED_GROUPS_ID = 'blocked-groups';
+export const BLOCKED_NUMBERS_ID = 'blocked';
+export const BLOCKED_UUIDS_ID = 'blocked-uuids';
+export const BLOCKED_GROUPS_ID = 'blocked-groups';
 
 export class Blocked {
   constructor(private readonly storage: StorageInterface) {}
diff --git a/ts/util/isBlocked.ts b/ts/util/isBlocked.ts
index 35ddb5cef15..27f67e336fe 100644
--- a/ts/util/isBlocked.ts
+++ b/ts/util/isBlocked.ts
@@ -2,12 +2,13 @@
 // SPDX-License-Identifier: AGPL-3.0-only
 
 import type { ConversationAttributesType } from '../model-types';
+import { isAciString } from './isAciString';
 
 export function isBlocked(
   attributes: Pick<ConversationAttributesType, 'e164' | 'groupId' | 'serviceId'>
 ): boolean {
   const { e164, groupId, serviceId } = attributes;
-  if (serviceId) {
+  if (isAciString(serviceId)) {
     return window.storage.blocked.isServiceIdBlocked(serviceId);
   }