list of subfolders where Userx does not appear in the security ACL

in a given folder, I want to list the names of all subfolders where UserX does not appear in the ACL.

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#easy enough to get all folders
set-location "\\server\share\"
$DocumentsFOlders=get-childitem | where {$_.psiscontainer}

#here I can't get the comparison to work,
#no matter if I use -notlike or -ne or -notmatch or -notcontains
foreach ($DocumentsFOlder in $DocumentsFOlders) {
     $documentsfolder.name | where {(($documentsfolder.getaccesscontrol() | select -expand access |
           select identityreference)) -notmatch "*UserX*"}
     }
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used separately, the command "$documentsfolder.getaccesscontrol() | select -expand access | select identityreference" returns a list of all Users in the ACL, and I can plainly see whether or not UserX is in the list. but it's a NoteProperty, and I can't seem to get it to compare to a string properly. in fact in some cases, it returns the same list of folder names whether I use -like or -notlike.