Disk usage discrepancy?

You shouldn’t have errors in the logs and all filewarkers should finish scan for each trusted satellites:

All untrusted should be deleted: How To Forget Untrusted Satellites

Did gc-filewalker finish the scan for all satellites?
Please also check for errors for the used space filewalker:

sls "used-space-filewalker" "C:\Program Files\Storj\Storage Node\storagenode.log" | sls "failed|error"

to check the used space filewalker processing (it should be performed for all trusted satellites):

sls "used-space-filewalker" "C:\Program Files\Storj\Storage Node\storagenode.log" | sls "started|finished"