Windows installer cannot upgrade files in C:\Program Files\Atlassian

Steps

1. Install Confluence 6.8.0 or 6.9.0 or 6.12.0 on Windows 10 with UAC enabled
2. Double click on the 6.13.0 installer
3. Install fails to move forwards trying to upgrade files in C:\Program Files\Atlassian

What happened...

See image below.

What should have happened...

The installer should have elevated the privileges in Upgrade Mode and be able to overwrite files in C:\Program files.

As a test, I installed Confluence 6.8.0 using Windows installer and I can upgrade again using the same installer to 6.8.0 without any privilege issue.

It sounds like the Windows Installer is still not elevating Prvileges in upgrade mode or something?
(We know in normal install mode is okay because it can write to C:\program files\atlassian)