Not sure this is a bug. The Support role is at the same distance as the Starbase. A Carrier is considered a Support ship, so it has to be close enough to deploy the fighters. In front of them are Interceptors, Assault and Escorts.
Capital ships are behind the Starbase/Support roles. Defenders probably should be back there defending.
Battle Behavior and ship roles have always been wonky. Go4Celerity made an excellent mod for that here, but I don't know if it works under 2.6