File System missing after update (5.6.21-2)

Hi all.

I have a RockPro64 running Linux 5.10.63-rockchip64, with Plex running as a Docker container. Everything was working fine yesterday, but today I saw there was an update in "Update Management" so I updated.

The file system which previously worked fine (6TB HDD) is now showing as missing (screenshots attached). The disk is still detected and shows up under lsblk, but the file system is missing. I have ~2TB of media on there, so I really don't want to reformat the drive. What can I do to fix this?

Thanks!

Somehow the mount has gotten screwed up, and the disk partition for sda doesn't show up in fdisk:

rockpro64:/:% sudo fdisk -l
Disk /dev/mtdblock0: 16 MiB, 16777216 bytes, 32768 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mmcblk1: 29.7 GiB, 31914983424 bytes, 62333952 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x6d666af0

Device         Boot Start      End  Sectors  Size Id Type
/dev/mmcblk1p1      32768 61702143 61669376 29.4G 83 Linux

Output of lsblk:

rockpro64:/:% lsblk
NAME        MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda           8:0    0  5.5T  0 disk
mtdblock0    31:0    0   16M  0 disk
mmcblk1     179:0    0 29.7G  0 disk
└─mmcblk1p1 179:1    0 29.4G  0 part /

sda was previously mounted and working fine. Not sure what changed.

rockpro64:~:% sudo fdisk -l /dev/sda
fdisk: cannot open /dev/sda: Input/output error

Going to open it up and check the cables. Nothing has been moved since I upgraded, so I'm not sure why this just started happening.

Plugged the HDD into my main PC, was able to read the drive. Switched it to a different SATA port on the PCI-E card, and now it's reading.