You can only mark as malicious if the rogue is being actively detected.
After a while the rogue is ignored and is not shown.
I have approx 8 rogues i see occasionally but they are only visible when freshly detected.
I would prefer to have a long list of all of them whether active or not but that is the way the ZD gui presents them. Perhaps Keith can explain the methodology and tuimeout reasoning?
It took a while for me to work all that out when setting up the ZD.