STEPS TO REPRODUCE
1. open it
2. create a partition table and partition ext4
3. open drive in file manager
4. try to move a file to the drive, it's impossible.
can't write to drive via file manager (unless you're using using acient software that allows opening gui as root)
should be able to write to drive without root access, or at least have a gui option to create a writable drive. Otherwise, what is even the point of the GUI if you have to drop to the CLI to change permissions?
no root as default makes more sense, since root access for a removable drive makes absolutely no sense. I think Gnome Disks has sane behavior in this regard.
*** This bug has been marked as a duplicate of bug 407192 ***