I built a new desktop about 4 month ago and I've had this issue ever since. On my task bar I have file explorer tabbed to it for easy access. I can click it once and it'll open up an explorer window. But if I right click the tab and click the "File Explorer" button it won't open a 2nd window. I have a laptop with windows 10 And i'm able to do it on there. I can't figure out why i'm unable to do the same on desktop. I've worked around it by just opening a folder on my desktop and that'll open a 2nd window for me but It's started becoming annoying enough that I want to fix it.