1) Could we have known this before? Any source of announcements? No, if it's a Preview action Microsoft can add to it, change it or delete it at will.
2) What is going on, and when will it be back? Who knows? I assume that something was broken with it which is why it was withdrawn. Hopefully it will come back but that is the problem with Preview actions.
3) Where to report this kind of issue? Should it go here? You can mention it here as you've done but there's nowhere official to report this. I know that sounds negative but that's the way it is.
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