Lync Presence not showing for specific user in SP2013

Question

I have a single user in our SP2013 farm whose online presence from Lync/Office consistently shows as "Presence Unknown" in SharePoint. Other users display their presence normally, and I've had the Lync admin check her machine for any issues. Lync appears to be working normally on her computer, and her online presence shows up correctly in Outlook. When viewing her name in any people picker field in SharePoint, or in a group membership page, the little square is white and it says "Presence Unknown" when you hover over it. I've been asked to troubleshoot this from a SharePoint perspective, and so far I've done the following with no effect:

• Removed the user from the group and re-added her
• Ran a full sync in the User Profile service application
• Removed the user from the site collection and re-added her

I've found several articles & forums detailing this issue, but those either don't have a solution or it's for ALL users, not just one.

How should I proceed to troubleshoot this Lync presence issue?

SharePoint 2013 Enterprise, Office 2013 on clients, using SharePoint Profile sync for users

UPDATE: I've also discovered that, although the user has an email address listed in their profile and on their My Site, they're showing up in the Users Lists for the site collection with no email. Not sure, but it's probably part of the same issue.

UPDATE 2: In an attempt to get the email address to show up, I followed the steps below with no success:

1. Delete user from all groups on the site
2. Delete user from Users List for site collection (she wasn't there?)
3. Delete user's profile in the User Profile service app
4. Run a full sync (SharePoint Profile Import)
5. Confirm user profile is there again and has email address listed
6. Add user back to groups on site

When I get to the last step, the user again has no email attached - in fact, some other fields are missing as well (Office, Department, Phone). These same fields work fine for other users, so it's specific to this one user.

Answer 1

The users SIP address has to match for presence to work. Once you get the users email address is imported to the User Profile it needs to sync with the User Info List. There are a couple of way to make this happen, but the easiest is to have the user "interact" with the site by creating content, adding a document or editing a list item. Following that activity the scheduled synchronization should run and update their user info list entry and the presence should work.