icloud for windows

I hit the same problem and have been working with Apple support on it for a couple of hours. It applies to icloud.com on Safari, Chrome, Edge and Firefox. Apple support have now referred it to engineering. I'll update when I hear more.

I have a further update but I am afraid it is not a positive one...

... Apple will no longer be supporting 'Find My Friends' on iCloud.com. It is only available through the iOS 'Find My' app.

Apple have not stated whether 'Find My iPhone' on iCloud will be enhanced to provide the same function as the 'Find My' app does on iOS. I expect that will depend, in part, on how their customers respond to the change. As someone wuth deteriorating eyesight, I certainly found it much easier to use FMF on a large monitor than on my iPad or iPhone. I have registered a complaint with Apple and would encourage other community members to do the same.