Anomalies, Incursions and other sites such as Factional Warfare sites might not respawn properly after the deployment of EVE Online: Inferno 1.2 on August 8, 2012.
We are aware of this issue and a team is currently conducting investigations with highest priority to find a solution as soon as possible. At the moment however we have no estimated time frame on when this issue will be fixed.
Please refer to this thread for further information and updates.
We apologize for the inconvenience resulting from this issue.