Per CSMS #15-000404:
When US Customs deployed functionality for processing air manifest transactions in ACE on June 6, there were some technical glitches (e.g., inability for carriers to see electronic release messages). To address these issues, CBP has devoted resources to stabilize the electronic manifest system for the air industry, and accordingly, has delayed deployment of additional ACE functionality that was to have occurred this past weekend. (ACE Deployment E Capabilities)