title: Telethon events.NewMessage() doesn't work
body: <p>I try to catch new messages in 4 certain channels, but not all channels work.
  If I write to account from my second account - script works.
  If there is new message in some channel - script doesn't see the event at all.</p>
  <pre class="lang-py prettyprint-override"><code>from telethon.sync import TelegramClient, events
  
  api_id = 11111
  api_hash = 'fjnbkdnslkfnbksbs'
  client = TelegramClient('test', api_id, api_hash)
  client.start()
  
  
  @client.on(events.NewMessage())
  async def handle(event):
      print('I see the message')
  
  
  client.run_until_disconnected()
  </code></pre>
  <p>What is the problem?</p>