Interesting points!

I did space it out so that the stem is a few MM's above the top of the steering tube, to give me ample room for adjustment. Check.

I did recently swap out the stem, and change the internal locking nut to the Deda unit (carbon fork and steerer). So it could be that the cups are still seating themselves, and need a few more tweaks to find their seating. This is most likely my problem!

Also, the stem isn't fully closed around the steerer, and it has been torqued properly.

So, I'll give it a while to allow the cups to fully seat, and see what happens. If I need it, it's good to know the extra clamp solution is out there.

Thanks!