WD MY Book not visible under catalina

The problem seem to be, that the driver/app from your WD My Book are not updated to Catalina (no more 32bit). In this linked thread they discuss this issue. You'll find in the link the new Catalina app WD Discovery, that has helped in most cases.

From release notes: "WD Discovery 3.5.152 -- 2019-10-23

• Fix for WD Discovery install and MCH mount issues on OSX 10.15.

"

Just install it and then plug your drive. It should be recognised then. And you will be able to install a crypto password if you like.

If not, then sorry, than that was not helpful for you. :)

Or try directly the universal firmware updater, same link a little bit lower:

"Description

This Universal Firmware Updater automatically detects and installs the latest firmware update available for your hard drive.

Supported Operating Systems

• OSX 10.09 and later

Instructions

1. Disconnect all other external drives from the computer except one My Book or My Passport.
2. Download WDFirmwareUpdater.zip to your desktop.
3. Extract the file using an extraction utility.
4. Once extracted, double-click on the file named WDFirmwareUpdater.dmg
5. Open the DMG from the Desktop and double-click on the WD Firmware Updater application.
6. Click "Continue."
7. Click "Accept" on EULA.
8. Please wait a few minutes until the required update modules are downloaded.
9. If the drive displayed is the correct drive, click "Continue."
10. Please wait a few minutes while your drive’s firmware is updated.
11. Click "Exit."
12. Safely remove the volume, then remove the USB and power cable. Wait 10 seconds and then connect the power cable and USB cable.
13. Reboot your computer.

Applicable Products

My Book, My Book for Mac, My Book Duo, My Book Pro, My Book, My Book Duo, My Passport Ultra Metal, My Passport Ultra (WD Backup), My Passport, My Passport SSD, My Passport Ultra, My Passport Ultra (USB-C), My Passport Ultra for Mac (USB-C), My Passport Go

Link here:

Download

From the WD board:

"Here’s a link to the WD security download for Mac: https://support.wdc.com/downloads.aspx?p=172#ctl00_WD_rpSoftwareMac_ctl03_lbtnExpand 2.4k

Install WD security and run the app. When prompted, plugin your Passport. It will then prompt you to enter your Passport password. From there, you’ll be greeted with options to update your security settings which include options to (1) remove your password, (2) set a new password, (3) add auto-unlock to your computer, and a few other items.

Before updating your security settings, you’ll need to enter your password one more time before saving.

I just did this and my drive works again on Catalina!"

https://community.wd.com/t/wd-passport-wont-unlock-after-mac-os-update/242697/7