I just bought a Seagate 2TB external HDD and hooked it up to my Xiaomi MI Box.
When I plugged it in, it asked me to format it, so I did.
I can see the HDD through Xiaomi's settings but the X-plore app and KODI won't detect it.
I now removed it from MI Box and plugged it into my PC and the drive won't show up even though it's visible through device manager.
What can I do?
I had the same problem as you, I used disk manager to remove all partitions on the disk, reconnected and then formated NTFS.
NTFS works with my Mi Box S.
Here is how to use diskpart if that doesn't work.
https://www.windowscentral.com/how-clean-and-format-storage-drive-using-diskpart-windows-10