Unblock question

I recorded ch41>46 FL in list 2 cue 2. I then went to cue 1 and recorded the same thing. Then I went back to cue 2 and tried to unblock cue 2. No matter what I tried, it would not unblock. Finally I tried "List 2 unblock" and that worked, i.e. it unblocked cue 2. Why? What am I doing wrong?
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