TIME MACHINE DOES NOT WORK PROPERLY IN IOS 10.15.4

Time Machine has become increasingly more unreliable with the later versions of macOS, and especially with all variants of macOS Catalina ... especially backups to a Time Capsule. However, it now seems to affect directly attached external drives as well. So far, I have not experienced any issues using TM to backup to my Synology NAS.

You can certainly try to remedy your current situation with using TM, but I would suggest that you consider using an alternative backup solution, like Carbon Copy Cloner instead.

In the mean time, if the TM backup process is "stuck," you can try these commands in Terminal to try to get it going again:

• sudo service com.apple.metadata.mds stop
• sudo service com.apple.metadata.mds start

Well whipping a HD is not the correct method, perhaps you meant you re-formatted (erased) it. Whipping it only makes it frothy and unhappy. :-)

Your External Hard Disk may not be in good health so please run First Aid on it several times to see if any errors appear. Time Machine will work just fine.

Also, by chance do you have any antivirus, cleaning or any other third party "maintenance" apps installed???

Another vote for Carbon Copy Cloner...

http://www.bombich.com/software/ccc.html

Give Tri-Backup a try, it can do everything & far more than TM can do...

https://www.tri-edre.com/english/tribackup.html 

Wiping was the spelling you wanted. :)

You can schedule backup-tasks: https://bombich.com/kb/ccc5/how-set-up-scheduled-backup