Why isn't the new version found by the old version?

https://www.sandboxie.com/DownloadSandboxie#DownloadInstructions states:

Upgrade: If you have an earlier version of Sandboxie already installed, you can let the installer upgrade (overwrite) your existing installation.

But 5.30 kept insisting no new version exists, so I had to download it manually.

Why is that? If it's not possible to upgrade inline, please remove the potentially misleading statement.