relatedly, I seem to be failing to attach a label correctly. I have M5 on top of M3 and want to attach the label to M3. Based on the manual, what I am trying should work, but its not. Advice?

% label ibias FreeSans 30 metal3
Moving label "ibias" from space to metal5 in cell current_sense.

This indicates that there was not actually any metal3 where the label was, or the metal3 did not cover the extent of the bounding box, or it was a mixture of metal3 and a metal3 contact, or there was metal3 but it was not in the edit cell; any of those will disrupt the labeling. If all else fails, use

label ibias FreeSans 30 -metal3

where the

-

indicates a "sticky label" that will be forced to have the specified type.