Try booting into Safe Mode to see the WD drives work.
Check the health of the WD drives by running DriveDx (free trial period) and posting the complete text report here using the "Additional Text" icon which looks like a piece of paper on the forum editing toolbar. You will need to install a special USB driver in order to access the health information of the external drives.
What is the exact model of your Mac? You can get this information by clicking the Apple menu and selecting "About This Mac".
If you run the third party app EtreCheck and post the complete report here, then we can examine it for possible clues.
Try running Disk Utility First Aid on both the internal drive and the external drive(s)....run First Aid on the hidden Container. Within Disk Utility you may need to click "View" and select "Show All Devices" before the hidden Container appears on the left pane of Disk Utility. You may also want to run First Aid on the physical drive as well.....this will be the item with the name/make & model of the drive. Even if First Aid says everything is "Ok", click "Show Details" and scroll back through the report to see if any unfixed errors are listed. If there are errors, then run First Aid again until the errors are gone. If the errors are not gone after several scans, then First Aid is unable to repair them. If this happens, then let us know which drive has the issue and the file system on it.
When you erased the external drives, did you just erase the existing volume, or did you erase the whole physical drive? Sometimes an external drive may have some odd partition layouts & hidden data on them which can cause issues with macOS, so it it best to erase the whole physical drive in order to create a fresh partition table along with file system.
Are you using any adapters to connect the WD drives?
Are these plain data drives with a single partition, or a Time Machine backup drive, or a backup drive using third party apps?