OK after being misled by false advertising and disappointed to find my 2017 LG 'smart' TV only has one USB drive and that is incapable of recording to a USB flash stick like my six years old Toshiba could easily do I went ahead and purchased a 1 Tb USB 2.0 Hard Disk - as recommended by LG Support.
Well guess what, shortly after recording about a dozen movies and programs on this disk the TV WebOs wiped the disk forcing me to take it out and reformat it again on my PC. As usual with this LG rubbish I sighed and reinstalled the disk. For two weeks it worked fine then, yesterday, LG issued a WebOs 'update' and yup, you guessed it, this wiped my hard disk yet again. This time I ran disk check utilities and certified the drive and cable is fine, no errors found. So if anyone has any knowledge of why the TV keeps corrupting the drive I would appreciate it.