I only noticed today, but with the on going recent issues with Outlook services I'm not sure if its been happening since the start.

On my Samsung Galaxy S3 Outlook.com Android App I am not able to sync all my e-mails, some messages appear but the majority do not. I do NOT have the same issue with the web version or Windows 8 App.

Here are some screenshots

Outlook.com Android App Screenshot

Outlook.com Web Version Screenshot *

You'll notice that in the Web Version I have 3 messages in my Inbox but the Android App is only showing 2 messages. The issue is not limited to my inbox only --- its affecting all my folders.

*I had edited the screenshot to remove any personal information