After a little experimentation, I believe I have found the answer.
The issue seems to be when Windows focuses on a program. For example, if you click outside of your web browser, you'll notice it grays out. Windows is no longer focused on it, it's focused on the window you clicked.
If you try running a program that's already open in another virtual desktop (depending on its ability to have multiple windows open), it will redirect to the applicable desktop.
Now, in the article below, it talks about "focus stealing". This is where a program steals the window focus for itself. This can and will affect your virtual desktops, so here are some instructions from it on how to prevent this:
How To Prevent Programs From Stealing Focus in Windows
It's not possible for Windows block all programs from stealing focus
and still work properly. The goal here is to identify the program that
shouldn't be doing this and then figure out what to do about it.
You may know what program keeps stealing focus, but if not, that's the
first thing you need to determine. If you're having trouble figuring
it out, a free tool called Windows Focus Logger (link in article) can
Once you know what program is to blame for the focus stealing, work
through the troubleshooting below to make it stop happening for good:
- Uninstall the offending program. Frankly, the easiest way to solve a problem with a program that's stealing focus is to remove it.
Note: If the focus stealing program is a background process, you can
disable the process in Services, located in Administrative Tools in
all versions of Windows. Free programs like CCleaner also provide easy
ways to disable programs that start automatically with Windows.
- Reinstall the software program that's to blame. Assuming you need the program that's stealing focus, and it isn't doing so maliciously,
simply reinstalling it may fix the problem.
Tip: If there's a newer version of the program available, download
that version to reinstall. Software developers regularly issue patches
for their programs, one of which may have been to stop the program
from stealing focus.
Check the program's options for settings that may be causing the focus stealing and disable it. A software maker may see a full screen
switch to his or her program as an "alert" feature you want, but you
see it as an unwelcome interruption.
Contact the software maker and let them know that their program is stealing focus. Give as much information as you can about the
situation(s) where this occurs and ask if they have a fix.
Tip: Please read through my How to Talk to Tech Support for help
properly communicating the problem. Last, but not least, you can
always try a third-party, anti-focus-stealing tool, of which there are
DeskPins is completely free and let's you "pin" any window,
keeping it on top of all others, no matter what. Pinned windows are
marked with a red pin and can be "auto-pinned" based on the window's
"Window On Top" is another free program that works in much the same
way. (Link in article)
Hope this helps!