Formatted and encrypted external drive using Disks app, but will not mount on either my Budgie Desktop or Budgie Laptop. Password lock/unlock shows as working.
Very interesting problem.
Googling you are not alone - this is a common issue with both nautilus and nemo. No real conclusion why it occurs it seems.
For me this link proved useful https://feldspaten.org/2019/07/19/linux-encrypt-external-hdd/
In summary - I formatted a luks disk with a strong pass phrase via Disks.
Then I installed the package:
sudo apt install cryptsetup
Disks said my usb stick was in /dev/sdc1
I connected the usb stick to the name “Cryptodisk” - choose whatever unique name you want.
sudo cryptsetup luksOpen /dev/sdc1 Cryptodisk
Then I created a ext4 partition for the stick called Cryptodisk
sudo mkfs.ext4 /dev/mapper/Cryptodisk sudo cryptsetup luksClose Cryptodisk sync
I disconnected the usb stick and reconnected it.
Finally I used nemo to open the usb stick and entered the strong passphrase.
I right clicked the pane and chose to open as root - at that point I could create new files etc.
you probably still have the mount open in nemo - unplug the device and reconnect - but dont mount via nemo util you have completed the instructions.