I've noticed recently - on multiple machines - that trying to install Fiddler defaults to an install path as the one depicted below. The same outcome is observed regardless if running setup as a local non-admin user, starting setup as a local non-admin user but running as administrator or simply logging in as an administrator account and starting setup. Yet Fiddler is successfully installed and runs just fine.
One of the other outcomes is that using the Start button to start Fiddler by simply typing its name no longer works - regardless if installing to the default path (present in the picture) or manually changing the install path to Program Files\Fiddler. In the first case that would make sense up to a point at least, since Indexing doesn't look in AppData by default, but not sure why it fails to work in the second case.
The latest attempt to install - and the same result observed as above - was using the latest version available today.