don't no if it is a generell problem
only had this on my external drive with win 10 (intern maybe also????)
i use terminal (console) also discover and pamac gui
and it stops update process after download
in pre xxxxxxxxx hooks
i watched in console output and i think i remeber it has something to do with
make a list of grub installed oses or backup it it was 1 or 2 of 11 prehooks session
sorry don't have loged it
but after i removed the usb cable the update process works on
Sounds like GRUB is scanning the external disk for bootable operating systems?
Whenever the Windows OS is referenced on this (and other Linux forums) you'll almost always find it mentioned with some associated Linux problem. Usually the post relates to a boot problem, ntfs read issue, or a networking problem, or some other other seemingly unrelated issue when Windows is installed. For some strange reason you almost never find the words "system works perfectly" in the same topic where Windows dual boot, NTFS, Samba, or "Wifi works in Windows" are mentioned.
All these weird issues that afflict Linux systems where Windows is installed could simply be indicative that Windows users as a whole are simply the most unlucky people on the planet. Or... perhaps...just maybe, it might be because Windows (and it's file systems) were never designed to coexist gracefully with Linux on the same system.
Naaah ... it must just be completely unrelated coincidences that almost all the posts where dual booting Windows is brought up Linux is disproportionately afflicted with problems. Although, it does kind of make you go hmmm ...
i'm lucky to have the option to just unplug windows 
