Applications appear on all desktops once clicked

[spiralofhope]

I've searched the forums briefly, but I wasn't able to find anything specific to this problem. I'm not quite sure how to shape a good search phrase though..

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I use a handful of workspaces, and I prefer to limit specific applications to specific workspaces.

- Launch an arbitrary application, e.g. `gnome-terminal`
- Right-click on the "Window Buttons" entry in xfce4-panel > Move to Another Workspace > (select a different workspace)
- Switch to that selected workspace
- Click on the application (it's not minimized)

That application becomes pinned to all workspaces.

Right-click the application title, the entry for "Always on Visible Workspace" is not selected.

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I've gone through various settings multiple times and I haven't run across anything obviously related to this.

Note that while this is a fresh install of Linux Mint, I'm re-using an old configuration which has gotten around, so it's quite possible I have funky leftover configs from other distro experimentation. Unfortunately there's no way I'll create up a new user to check differences between the two. =)