I don’t seem to understand why I receive a DRC error here for pad annular ring here. Clearly the copper around the pad exceeds the circle highlighted; what is happening? Have I failed to understand something about pads or annular rings?
For me this looks like the annular ring of inner copper layers is too small. By default, annular rings on inner layers are always circular, no matter what shape is used on the outer layers. You can see the inner annular rings by hiding the top/bottom copper layers in the layers dock.
The width of the inner annular rings can be configured in the Board Setup dialog under the Design Rules tab.
Indeed that was the case. I’ve set the inner copper annular rings to “Full Size” and the DRC errors are no longer produced. Thank you.