Lync 2013 organization intergated with Exchange 2010 (AD is the storage of photo).
Some lync 2013 clients do not see some colleagues's photo in their contact lists.
How can we "push" photos periodically to display contact info correctly?
Microsoft ApplicationsMicrosoft Server AppsContact Management
it will depends on the connectivity of lync 2013 to the AD server.
If the AD is not responding (get back in time), the photo will not show up. (i.e. if are on VPN, slow link or etc)
The photo is not stored locally.
you can try to refrsh the lync address book to see whether is this once off.