Not sure where to put bugs, but there is definitely one in the iPhone Lync app available over the past week.   Two people at my company are seeing messages appear in the notification screen when our phone is locked.   However, when we unlock our phone and open the app, there is nothing in the chat window.  

Is this a known bug?  

Hi,

Please remove the lync client from Iphone, download and install the latest version in the App Store. Please check the problem again.

Did this help??? I'm having the exact same issue. All push notifications are lost when I open the Lync app!!!

Has anyone had any luck resolving this? 

This does not help. I have removed the Lync 2010 twice and reinstalled, but the problem persists. This is highly annoying. Can't use Lync 2013 as the exchange server is not compatible with it. Someone please fix this bug.

Try wync on the app store. It may work for you.

You can also see it at www.wync.me

The Exchange server at my company is not compatible with the Lync 2013 client. Are there other chat clients for iOS that will work with Lync?