Let's say I'm doing a run. I break the ice in front of a subsystem and then access it and perform the enact command maneuver. Do I now have access to this subsystem so long as I don't "move" or will I be locked out again when the ice comes back online?

The rules seem to imply the latter but it feels like it should be the former. It feels weird that I would, for instance, get access to the doors system, be able to open one door, and then have to break through the ice again.

Can anyone quote some RAW to me to confirm it one way or the other?

I just got an official reply from the question form.

Quote

You have access until the ice reactivates. Technically, you always have access, but if the ice is active, usually it stops you from getting in.

Hope this helps!