@jpeg729 I’m not sure this is different or not (maybe I should open a new thread), but finally I solved this issue.
In my case, it always output zeros when I set the batch size to “1”, but in a different batch size it outputs some various vectors and learns correctly.
I’m still trying to figure out why this is happend and what part of my code makes this issue (in 600 lines code). I just note this since it might be helpful for someone else.