Due to mixed content warnings, I am unable to even get the sign in page to load properly. This is happening in all recent versions of Firefox, Chrome and Internet Explorer 11, with or without addons/extensions. I have cleared cache and cookies as well, just in case.
Both static assets and javascript are returning similar errors.
Here are some of those errors on page load when visiting https://connect.garmin.com/ :
Loading mixed (insecure) display content on a secure page "static.garmincdn.com/.../icon-logo-chrome.png"[Learn More] signin
Loading mixed (insecure) display content on a secure page "static.garmincdn.com/.../icon-logo-firefox.png"[Learn More] signin
Loading mixed (insecure) display content on a secure page "static.garmincdn.com/.../icon-logo-ie.png"[Learn More]
These errors prevent the username/password form fields from even loading.