Newbie freezing vise but move workpiece?

Hi all,

I'm new to sprutcam (running version 8) and have hit a snag that should be an easy fix, but I cant seem to solve-

I have a part that needs two setups- clamp left end in vice, mill the right end, then rotate 180deg (about z) so the milled end is in the vice and the back end can get milled.

Easy enough.

I have a G54 defined for the first setup and G55 for the 180 degree rotation and the part rotates perfectly as needed.

My problem is that i have a vise defined as a fixture and when the part rotates, the vise goes with it. I need the vise to stay put so the part can flip relative to fixture.

What am I missing?

Thanks in advance,
Michael.