Invisible file on Windows NTFS disk [duplicate]

On a windows 10 Home system there is a file which does not appear to have any name. It does not appear in either Explorer or with the dir command. Macrium backup tells me (using the total amount backed up) that it's backing it up.

However, it gets backed up and is also visible to WinDirStat with name <unknown>. As it's 70GB it's clogging up my backup disk and I want to delete it. I've tried chkdsk but that doesn't throw up any errors.

It's not on the system partition, which might make things easier.

I've run WinDirStat in 3 modes: logged in as admin, logged in as a user, and running as admin while logged in as user. And get 3 different results for the size of the unknown file: 142.7GB, 70.5GB and 738MB respectively. It looks as if there are files there which have different owners and so give different total sizes - but I thought that admin accounts had access to all files.

Any ideas how to get rid of it (or at least identify if it's safe to do so)?

I found the problem.

It appears that WinDirStat only sees files that the current user has access to. @Bob suggested I use WizTree which uses the MFT directly. Comparing the two I found some folders which had genuine files in them (hence the backup size) but an unknown owner, and no access rights to myself. Explorer and WinDirStat reported them as zero size. Changing ownership and access rights cleared up the situation.