Time Machine - Not able to Browse backups

Summary:

• Unable to browse in ‘Enter Time Machine’ to restore an earlier version of a file
• Unable to select a Time Machine backup window from the right side time list although the cursor does highlight a time.

Background:

• macOS Monterey 12.5 running on 24in M1 Mac
• Single User with admin rights.
• All user data held on external 3TB Thunderbolt drive (LaCie)
• Mac 256GB SDD is only used for the OS
• Time Machine configured to external 2TB USB drive (Fujitsu)
• Have changed User Home directory using System Preferences, Users & Groups and right click on user name to change home directory (used a temporary admin user in order to do this)
• Using Finder, the Home Directory is confirmed as ‘LaCie Data’
• Using Finder, clicking on Documents shows my data folders on the LaCie drive
• Movies, Pictures and Music are all in the ‘La Cie Data’ directory
• Selecting Music, Movies or Pictures from Favourites, takes you to the same (correct) directory.
• The Music, Movies and Pictures apps all work correctly and with all files accessible.
• Time Machine has been erased and reset a number of times. (It takes about 4hrs for the first full to complete).
• The amount of disk used on the Time Machine disk at the end of the first back up represents a ‘copy’ of the data disk, approx 1.2TB.

Symptoms:

• In Finder, selecting Time Machine shows the backups that have been performed. All good so far.
• In ‘Enter Time Machine’ you can see the ‘Now’ window with the directory structure.
• You cannot use the up/down arrows to browse to an earlier version.
• You can use the right hand time line to move up and down (with the highlighted backup time changing to red), but you cannot select a backup.

Result

• Time Machine is not providing a back up service and I cannot restore earlier files if needed.

What have I done wrong?