I'm sure someone has asked before, but I can't find it. It's difficult to come up with the correct query or title for this topic. The issue sounds similar to this known issue:

Can't Fix: Taskbar buttons for Universal apps remain on the Windows taskbar when the app is moved to another monitor.

I don't think this is a "universal app". I'm guessing universal app is what I refer to as a "modern app" or "MS store app". This app is a win32 app if that's the correct terminology (an exe file). The app is Kaseya VSA Live Connect. I have 4 Live Connect remote control windows open with a different window on each display. I'm on Win 11 24H2 Enterprise build 26100.3037 and DF Pro 11.1.1.

I would like the Windows taskbar (the built-in taskbar on the primary display) to only show the Live Connect window that is on that display. The 3 DF taskbars are correctly showing the taskbar button for the window on their respective displays. The Windows taskbar is showing all 4 windows which means clicking it doesn't foreground or restore the window. Clicking the button shows all 4 windows; I have to figure out which is the correct one and click its preview.

There is an option in Windows "when using multiple displays, show my taskbar apps on: taskbar where window is open", but it's greyed out unless I enable "show my taskbar on all displays" which conflicts with DF taskbars. The "combine" options in Windows don't seem to make a difference for this issue. Kaseya Live Connect seems to be the only app that's doing this. Excel, Greenshot, Firefox, and Windows Explorer behave how I expect; the Windows taskbar only shows the corresponding Window on that display if there are multiple windows open for that app. Is this due to something stupid that Kaseya is doing? I hate their software; it wouldn't surprise me if they're ignoring some standard and doing whatever tf they want to do.