Having trouble loading an address in a new Website tab? That happens occasionally in the Teams web app because certain sites can prevent themselves from being embedded in other sites.
When a site won't load, a banner appears saying If your site isn't loading correctly, click here. Go ahead and click there for options.
The next page gives you three options to solve the problem:
Click View the site in your desktop app to open it in the Teams desktop app, where it should work fine.
Click Go to the website to open the site in a new browser tab outside of Teams.
Click Reload this tab to try again.
To pull up those options again, just click Reload tab in the top right corner immediately when you realize there's an issue. You should also hit Reload tab if a tab that used to work is suddenly acting wonky.
Remember, these issues don't usually pop up in our desktop app, so if you're frequently running into this problem, consider going over there.