[Sinapus]

It won't deploy all of them. It will deploy as many as it can in one turn, leaving the others in the bays. If you want to drop all mines in that place, then you would have to add an extra movement set that moved the ship away from the launch point then back at least one turn later to launch the rest of the mines.

Personally, I just altered the settings in components.txt to let you launch enough mines to empty the bays, but not to allow the "one mine layer plus a bunch of cargo bays" strategy.