You cannot do a local preview of an album produced by Lizard, Photoblogger, Plain, Projector, Story, or Tiger by opening the album's index.html file in your browser. The failure produces problems such as only the first 20 thumbnails showing, or missing navigation on the lightbox slide image.

For security reasons, all browsers now block attempts by a Javascript routine to open a local file (like a JSON file), since the browser can't verify the domain origin of that file. Once the album is uploaded, and is being viewed from a server, the browsers' security requirements are met, because the JSON file is coming from a domain (i.e., your domain) that matches the domain that is serving the HTML page.

In practical terms, this means that local preview of an album that's using a JSON-driven skin like Lizard, Photoblogger, Plain, Projector, Story, or Tiger will fail. This includes double-clicking on the index.html file of the album to launch it in your default browser. There is, in fact, nothing insecure about these albums. It's just that the browser has no way of knowing that.

There are some convoluted ways to launch a browser with this protection turned off, but that would leave you vulnerable to malicious websites, so using this approach isn't recommended.

The current version of jAlbum has a very effective workaround, however. Under Tools/jAlbum (Windows/macOS), Preferences, General, Preview, choose Use embedded web server. With this choice, the local preview (F12) quietly launches jAlbum's internal server, so the preview is actually being presented by a server. This satisfies the browsers' security requirements, and the local preview behaves normally.