Alt-tab to an All Workspaces window jumps to other workspace

[thoughts]

I use multiple workspaces, with some apps like Firefox set to "Always on Visible Workspace". A few months ago an annoying bug started happening: whenever I use Alt-Tab to switch to Firefox, the window manager will throw me to a different workspace, in addition to switching to Firefox. It's not one particular workspace; it seems random.

Has anyone else seen this, or have any idea how to fix it?? It's super frustrating. I keep hoping that it'll be fixed when I install the daily/weekly software updates, but no such luck.

(And it's not just Firefox; it happens with any app/window set to "Always on Visible Workspace".)

I'm running Linux Mint 13/Maya with MATE 64-bit.

Thanks,
Anthony DiSante