Macrium 8 folder backup depends on the signed-in user for no obvious reason

I use Macrium Reflect 8 (workstation edition) on Windows 11 Home in File and Folder backup mode to backup up the entire contents of a single folder tree on the Z: drive which is held on an internal disk (ie not the C: system drive that contains Windows, Users etc).

Within that folder tree, there is a folder named “Censuses”.

Within “Censuses”, there are two folders named “Censuses.1841” and “Censuses.1851”.

The contents of “Censuses.1851” are very similar to the contents of “Censuses.1841”, and, as far as I can tell, the permissions and owners of both sets of contents are identical.

My problem is that, if I perform a full backup when signed in as one user (with administrator access), “Censuses.1841” and its contents are included in the backup, but “Censuses.1851” and its contents are not included. If I then perform an incremental backup when signed in as the same user, “Censuses.1851” and its contents are still not backed up. However, if I switch to a different user (also with administrator access) and perform an incremental backup, “Censuses.1851” and its contents are now backed up correctly.

I am frankly baffled by this behaviour. Any ideas for how I can successfully back up everything as the first user?