This only happen to your lync client or is a general issue?

Could you try re-install Lync Client?

Check this post, it's seems to be the same issue.

http://social.technet.microsoft.com/Forums/en-US/2775ed03-c0e0-46e0-99b8-2fe6a76663c1/group-presence-counts-not-updating-after-security-patch-with-cu8

Hi , I've created a new group, added new members. In Lync client it shows me my group and in brackets there is a value of available memebers and value of all members of my group. I've noticed that the value of available members is shown wrong - it is "0". Does anyone know what this is caused by?

greetings

Paul

Hi Paul,

Are those members availables, I mean are in Available/Busy Presence State?, if they are in Away/Off Work/ or something like that, the counter will show 0 value.

 I have 7 members of my group, 5 are in green (are available), 2 are off work, and the counter shows 0/7.

Hi,

If the issue happen for all users, please install the latest update of Lync.

http://technet.microsoft.com/en-us/lync/gg131945.aspx