I experience an issue with LACP
Hardware: SRX340/345 ; EX2200
Software: SRX340 : 15.1X49-D50.3; EX2200: Junos 12.3R12
If all members of AE interface are not connected while booting up, traffic does not passthrough properly. JTAC confirmed it is a bug. They are working on the bug fix. Please keep an eye the resolved issues on new JUNOS releases.