External HDD - Only one partition detected

I have recently installed CoreELEC onto a generic S905x Amlogic box and I’m very impressed so far.

However, I have an issue with an external HDD (4TB WD Passport) that previously worked fine with 18.1 Leia. Namely only one of the two partitions on the HDD is showing in System Info > Storage.

“WD Unlocker” is visible and accessible but there is another partition called “My Passport” containing all of my media which is not showing/detected.

Ironically if I unplug the drive CoreELEC confirms I have successfully removed two “storage devices” (i.e both partitions) - See the second photo where it confirms “My Passport” has been removed.

Am I missing something obvious? I’m conscious that it’s an external HDD which draws powers via USB but A, it worked on the same device under 18.1 Leia and B, if it was a power issue I don’t understand why one partition is detected and accessible but not the other.

Any advice would be appreciated.

Just an update. If I ssh into the device and “df” it it just shows the one partition.

If I plug the HDD into a Ubuntu laptop and “df” it it shows two partitions including the one with all my media on it.

Consider this resolved. Albeit I had to format the device. Now the correct partition shows.

Still unclear why Ubuntu and Windows 10 could see it but not CE.

What format was the partition?

NTFS, sorry for slow reply.

Do you know what OS the drive was formatted on? Or better yet, the partitioning system used? (GPT, MBR, etc)