Q: icloud stop sync (both windows 10 and 7)

I had icloud running like 3 years and working like a charm. (Windows 7, Windows 8 and even Windows 10 machine)

I have no idea at all (whether it's update/upgrade issue), icloud just stop working, nothing sync;

I found all suggestions (including reinstall, task manager and end all process, clear cache.....) but nothing works.

Anyone experience the same? If yes, any solution/suggestion?