It should contact with the FA pressed. Are you able to free the lower from the rifle? If you depress the hammer it looks as if it may go, may have to push out the hammer retaining pin and deal with just the upper.
Possibilities:
Cam pin suck, buffer retaining pin wedged in there, somehow the firing pin retaining pin is wedged...curious now.
Possibilities:
Cam pin suck, buffer retaining pin wedged in there, somehow the firing pin retaining pin is wedged...curious now.