Thank you for reporting this.
Does the browser you use on the computer where the sidebar doesn’t load have any ad blocker plugins? I am using Firefox on Windows 10, and the sidebar seems to work fine on the link you provided.
The fact that you see the sidebar for a few seconds and then it disappears, means that either some JavaScript on your site is hiding it, or you have a browser plugin that does it (e.g. an ad blocker that mistakes your widgets for ads)