The reason is the Live User is deleted after the creation of the installed User, Because I use Penguins Eggs to capture an existing installation my guess is that user 1000 is used at the time of capture, I haven't looked into how to re-base it yet but will in the next public release, the issue is if I change it now then you'll have to change the file permissions for them, so I might have already missed adding this change. Here is how to fix it and it mentions that if you do it the other way you have to change the installed file permissions, so it may be easier to just run the top command on your existing files.
Change File Ownership: If this causes file permission issues with older backups, run sudo chown -R <your_username> /home/<your_username>
Correcting the ID: You can manually change your UID to 1000 using usermod, but this requires updating file permissions for all your files.