USB Sticks not getting properly recognized Two of my USB sticks (Lexar and PNY, both 32 GB) are not getting recognized correctly by macOS Sierra. Both worked before (one formatted with NTFS, the other with FAT32); they were then used as installation media for upgrading a couple of MacBooks to macOS Sierra.

They have since been tested, getting reformatted by Linux as well as Windows 7 between tests, but the following output is always the same using diskutil list:

/dev/disk3 (external, physical):
       #:                       TYPE NAME                    SIZE       IDENTIFIER
       0:     Apple_partition_scheme                        *32.0 GB    disk3
       1:        Apple_partition_map                         4.1 KB     disk3s1
       2:                  Apple_HFS                         311.3 KB   disk3s2

After plugging them into the MacBook they are still working on Windows and Linux (they were tested by writing the whole stick and verifying the data).  I also deleted the partitions using fdisk in Linux.

Is there a way to repair this behavior? And if not, is there a way I can redefine how the partitions are getting assigned by macOS so that I can still manually mount them?
There's nothing wrong with what you are seeing.  That's the partition scheme for your bootable USB.  When you format it, you are not deleting the partition, just "blanking" the active partition.

Formatting a partition is not the same as deleting the partition.

To get back to a "single" partition (this is what I am assuming you want to do), issue this command in diskutil

diskutil partitionDisk /dev/disk3 1 GPT HFS+ NAME 100%

This command will permanently delete anything you have on the device.  Make sure you are using the correct device identifier

Be sure to replace "NAME" with the name you want to give to the USB.

Your drive partition map will be wiped, and the HFS+ (Mac OS Extended) file system installed.

What I suspect happened in your case is that you didn't "write" the new partition scheme to the USB.  This is done by issuing the "w" command.  Linuxhelp has an excellent tutorial on fdisk



More info can be found by typing man diskutil