Below is that 14 year old thread that Leon mentioned. In it a variety of experienced hobbyist chimed in, and most conclusive is the last post in the thread by Bob Lemke, who investigated and wrote a SCD article about this subject, and Bob even implicates the likely culprit behind these Neilson's W572 cards.
https://www.net54baseball.com/showthread.php?t=123916
Brian