your initial post is correct with the pipe off the actuator completely the turbo should boost until it gives up or the engine does.

with the amal valve removed and the pipe connected to the actuator (from the compressor housing or similar) the turbo should boost until the wastegate opens at what even its set to

With an amal/bleed/boost controller valve inline the turbo will boost until the wastegate opens PLUS any bleed off from the amal/bleed/boost controller valve. (So will at higher boost)

sounds a bit strange that yours is not behaving this way, definately no boost leak? have you tried joining the hoses you took off from the amal valve to see if it will boost to the actuator setting?