Not sure, it could be a number of issues most likely it's related to either incorrect compound or pad usage. Swirls could be marring from an aggresive compound that they haven't polished out.
I use the edge of my pads from time to time even though I agree with the flat pad rule you stated earlier. I even used a wool (acrylic) pad on this panel and used the edge to speed up cutting in certain areas.
closeup:
Risky I know and not technically perfect but I have a little experience and know what I am doing. I did leave behind hideous marring but corrected the swirling and holograming behind and acheived this finish after an alcohol wipe (no lsp):
closeup:
