Bug report - beam start/stockpile

Planet Drasta has a stockpile of 20K copper.

I'm upping speed and cargo and have a speed pilot to get it all down to my base. I go a bit overboard and end up with Drasta, level 46, 38, 39 flipping to beam mode.

Without a manager, it slowly pulls down the stockpile. Really slowly.

Add a pilot or cargo manager, the stockpile flickers without pulling down at all.

Is this a bug or a feature?

Is beam mode the max possible speed, and only new production will be brought home from the planet?

It's only 19k, thank god, but checking how it works ....?