Removable disks vanishing from desktop when mounted

Hi.

I have "removable media" selected to show up as desktop icons, and for the most part memory sticks do so. I've noticed that some external drives don't, however. As soon a they're mounted, the icon vanishes from the desktop.

If it happened with all of them, or none of them, I'd understand. What doesn't make sense is that it's seemingly random. I have 1-TB USB drives that vanish, and seemingly identical drives which remain visible.

Am I just late for the party and this has been known forever?

Curt-