Reading a cropped buffer~ into an external takes too long

Hi,

I'm using a large buffer~ (600000ms) to record into; when I stop recording, a [crop 0 $1] command automatically resizes the buffer~ to my desired size... or so it appears.

Then if I load the buffer data into my external, it takes a long time, as if the buffer~ was still the initial (big) size.

If instead I [writewave] the sound to a file, then [replace] it into the buffer~ and load that, it works instantly, as it should.

Any idea how to make Max refresh the memory size taken up by the buffer~ after a [crop] command?