WebGL: Syntax error for unrecognized expression from UnityLoader.js when clicking on page link.

I have a handful of WebGL projects hosted on a GoDaddy Windows (Plesk) server.

Each one throws a JavaScript error when I click on a link within the page, but outside of the canvas element. For example, the home button.

Firefox, narrowly, gives the most detailed error in the console: Invoking error handler due to Error: Syntax error, unrecognized expression: ../../Blog UnityLoader.js:1:29721

There I used a relative link, but I've also tried hard coding the complete URL and the same error occurs.

An example page.

Not sure what I could be doing. Game controls and browser buttons all work fine.