WD External Drive shows empty in Finder, won't unmount or repair unless unplugged
First, try running First Aid while the device is readable. If that doesn't fix the issue, then you can try using Safe Boot to isolate and fix issues with your Mac. This does not seem like an issue with macOS, more like an issue with your drive.

What is your External Drive's format? If you will be using it only on a Mac, then I would recommend formatting it to HFS (macOS Extended) or APFS. NTFS and FAT32 are not always the best choice on macOS. Before formatting, make sure to copy and paste your files to your Mac so that you can put them on the drive after formatting.

Before formatting, can you see if the data is still accessible via Terminal. To do this: cd /Volumes/YourDiskName then ls to see all the contents.

To format the drive (This will erase all data):
1. Open Disk Utility
2. Select your drive
3. Select Erase (at the top)
4. Select the format APFS or macOS Extended
5. Select Erase

If you would like to report this to developers, you can try submitting feedback to the manufacturer of the Disk or to Apple.

Here is the link to submit feedback to Apple: https://www.apple.com/feedback/

Good luck!