I have encountered something similar on Linux, where copying was delayed for a long time, stuck at the very end of the progress bar, and it was a communication issue between hardware and software, where the software was showing the copying progress without getting proper feedback from the hardware regarding the current status of the copy process. In other words, for lack of proper hardware feedback, it was trying to estimate the time remaining, and it was doing a bad job at it.
I believe something similar is happening here. Except that the software here is stuck attempting to get feedback from the hardware at the beginning.
In the case of Linux, I simply tweaked the system to shorten the wait time and forget about the hardware confirmation (an advice the community received from Linus himself).
In the case of Windows, since the software is closed source, I believe you'll need to wait until Microsoft releases a patch that fixes this software-hardware communication issue. I expect that this happens only with certain types of hardware (hard disks).
It's not surprising, as Windows 10 was released prematurely, with a ton of software-hardware and driver issues. In fact, you may be lucky this is the only problem you've encountered. Microsoft has been patching things ever since, trying to bring Windows 10 into a stable shape.