I'm trying to update the internal git (via the settings) and it fails when it tries to extract: Unable to extract PortableGit.gz

I've updated 7-zip to the latest version - makes no difference.

7-Zip [32] 16.02 : Copyright (c) 1999-2016 Igor Pavlov : 2016-05-21

Scanning the drive for archives:
1 file, 35477168 bytes (34 MiB)

Extracting archive: C:\Users\JT\AppData\Local\Atlassian\SourceTree\PortableGit.7z
WARNING:
C:\Users\JT\AppData\Local\Atlassian\SourceTree\PortableGit.7z
Can not open the file as [7z] archive
The file is open as [PE] archive

–
Path = C:\Users\JT\AppData\Local\Atlassian\SourceTree\PortableGit.7z
Open WARNING: Can not open the file as [7z] archive
Type = PE
Physical Size = 35477168
CPU = x86
Characteristics = Executable 32-bit
Created = 2017-04-05 14:33:08
Headers Size = 1024
Checksum = 35481204
Name = 7zS.sfx.exe
Image Size = 503808
Section Alignment = 4096
File Alignment = 512
Code Size = 382976
Initialized Data Size = 106496
Uninitialized Data Size = 0
Linker Version = 14.10
OS Version = 6.0
Image Version = 0.0
Subsystem Version = 6.0
Subsystem = Windows GUI
DLL Characteristics = Relocated NX-Compatible TerminalServerAware
Stack Reserve = 1048576
Stack Commit = 4096
Heap Reserve = 1048576
Heap Commit = 4096
Image Base = 4194304
Comment = FileVersion: 16.4.0.0
FileVersion: 16.04
ProductVersion: 16.4.0.0
ProductVersion: 16.04
CompanyName: Igor Pavlov
FileDescription: 7z Setup SFX
InternalName: 7zS.sfx
LegalCopyright: Copyright (c) 1999-2016 Igor Pavlov
OriginalFilename: 7zS.sfx.exe
ProductName: 7-Zip

Path = [0]
Size = 34994208
Packed Size = 34994208
Virtual Size = 34994208
Offset = 477184
–
Path = [0]
Type = 7z
Offset = 515
Physical Size = 34993693
Headers Size = 62116
Method = LZMA:27 BCJ2
Solid = +
Blocks = 2

Sub items Errors: 13

Archives with Errors: 1

Sub items Errors: 13