Fix compatibility of Chrome Extension with Specific Website

I have a chrome extension that isn't working on a specific website an I need the issue identified and hopefully fixed. A quick description is the user logs in to the plugin, it displays a sidebar which controls the plugin. On the website where the extension doesn't work, the sidebar appears in the website login screen but once the user is logged in, the sidebar disappears and doesn't interact with the page so essentially doesn't work. I have attached a small video displaying what is happening. In the video, you see the sidebar on the right of the page at the webpage login screen. Once the user logs in and gets to the main page, the sidebar disappears. I will provide the test credentials for the extension and have the source code as well obviously.