Could not mount “AppleAPFSMedia”. (com.apple.DiskManagement.disenter error 49217.)

Boot into Safe Mode according to Start up your Mac in safe mode - Apple Support and test to see if the problem persists. Reboot normally and test again.

NOTE: Safe Mode boot can take up to 3 - 5 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

The Safe Mode boot is totally benign and a good first fix attempt to try for many problems.

How was the WD My Passport drive formatted?

Did it come with some software that you installed?

Have you installed or run any "cleaning", "optimizing", "speed-up" or anti-virus apps on your Mac?

Welcome to the Apple Support Communities.

Can you mount in Safe Mode: How to use safe mode on your Mac - Apple Support?

Can you run First Aid: How to repair a Mac disk with Disk Utility - Apple Support?

Jack

From research, Disk Drill seems to be malware. You can’t restore data from an encrypted disk anyway.

WD My Passports are poor quality and fail quickly. I’d suggest replacing it with a LaCie or G-Technology drive.

There is nothing risky about Safe Mode.

What recovery software did you install?