iTunes on Windows cannot enable iCloud Music Library

Windows iTunes cannot enable iCloud Music Library.

I still manage my 13-year old music library using iTunes on PC, which includes tons of ripped files from CDs. On Monday I ripped two of my newly purchased CDs and I checked out they were available on my iPhone and iPad, with no problem.

But today (Wednesday), all of a sudden, when I raunched the iTunes program, it kept "trying" to make available iCloud Music Library (iML) and then failed, showing the message that it cannot make it available and please try again. Of course the Apple Music files I added were all greyed out.

So I try turning off and on iLM in Preference, but when I turned off, all of my Apple Music files were gone (even though they are still there when I opened the web version of AM.) I also tried signing out and in, but still it made no change at all.

I checked my internet connection and my computer - there were no problems. Why is this issue suddenly happening?