High Sierra disk space over 120Gb

I apologize in advance for the length and detail of this question. I have been through three AppleCare visits without any workarounds or fixes so I want to kick it to the group with as much detail as possible.

Last weekend, 9/23/17, I worked on my computer (MacBook Pro, Retina, 13", Early 2015, 250 Gb) and another, both under OS 10.12, to try and free up hard drive space that was being taken up by Mail. I mention this only to set the background because I know specifically through doing that how much drive space was available and how much was taken up by System prior to the High Sierra install. Prior to the High Sierra install on 9/25/17 my computer had just over 100Gb available drive space. After installing High Sierra there is between 39 and 53Gb available and the System takes up 150Gb.

The statements about System size are based on the About This Mac/Storage report

and Disk Utility

The problem is not just the size that System is taking up, but that any check of the specific System or Library folders does not add up to anywhere close to the size that is being reported. I also cannot, other than the two reports above, confirm the space available numbers that are being shown. The file sizes are fluctuating significantly, but I ran du -shc | sort -n several times to try and show the actual sizes of the individual folders and I am getting results that do not match the above.

du: private/var/db/ConfigurationProfiles/Store: Operation not permitted

du: private/var/folders/zx/q8r82tq12qz0815ybm06bb0h0000gq/0/SafariFamily: Operation not permitted

du: private/var/folders/zx/q8r82tq12qz0815ybm06bb0h0000gq/0/com.apple.LaunchService s.dv: Operation not permitted

du: private/var/folders/zx/q8r82tq12qz0815ybm06bb0h0000gq/0/com.apple.nsurlsessiond : Operation not permitted

du: private/var/folders/zx/q8r82tq12qz0815ybm06bb0h0000gq/0/com.apple.routined: Operation not permitted

du: private/var/folders/zz/zyxvpxvq6csfxvn_n00000y800007k/0/com.apple.nsurlsessiond : Operation not permitted

du: private/var/folders/bg/5mbvpkz53gv6g4hjkd3w2zp00000gp/0/SafariFamily: Operation not permitted

du: private/var/folders/bg/5mbvpkz53gv6g4hjkd3w2zp00000gp/0/com.apple.LaunchService s.dv: Operation not permitted

du: private/var/folders/bg/5mbvpkz53gv6g4hjkd3w2zp00000gp/0/com.apple.nsurlsessiond : Operation not permitted

du: private/var/folders/bg/5mbvpkz53gv6g4hjkd3w2zp00000gp/0/com.apple.routined: Operation not permitted

0B Groups

0B Network

0B User Information

0B Volumes

0B cores

0B etc

0B tmp

0B var

1.0K home

1.0K net

1.1M sbin

2.6M bin

4.0K installer.failurerequests

4.5K dev

5.7G System

7.7G Library

8.0K Incompatible Software

8.0K Shared Items

11G private

20G Applications

43G Users

88G total

685M usr

The total space from the du report is only 88Gb and the individual folders, Users, Apps, etc. match the size results you would get if you did a Get Info on those folders. Is it possible that any of the /private/var files is accounting for the remainder of the size? Is About This Mac and Disk Utility just incorrectly reading the file sizes?

Any ideas would help. So far at the recommendation of AppleCare I have reset SMC, performed Disk Utility Repair and reinstalled High Sierra. No change in results with any of the above.

Thanks