One visitor who placed an order did not appear in the ecommerce log so I segmented for his IP with &segment=visitIp==1.2.3.4 and his visit did not appear at all. Segmenting for other IP addresses do appear as they should. Does this likely indicate that the visitor did not have javascript enabled? What percentage of visitors normally do not enable javascript?
Could be, or that he uses adblock or ghostery browser ext, etc.