Probably because it's much stricter about allowing third-party scripts and cookies on your computer.

Go to "Settings -> Privacy & Security" and (temporarily) set "Enhanced Tracking Protection" to "Standard". If that works, you've found the problem. Set it back to "Strict" and then add an exception.

To add an exception for your health insurance website, browse to it and then click the shield icon in the address bar. Flip the toggle switch to turn enhanced protection off.