[Jungsuk Kang]

This month I have encountered same problem that Rosa Linda Román had. I somehow I just found solution below(you can skip no.1)

1. I selected clip which not showing and copy-paste it to exact same position. So 2 same clips on timeline. doubled up.
then It worked. Clip is showing with no problem in viewer. So I deleted 1 of them then It goes black again.

2. So I tried many other things, then found solution. Select your clip and right-click. choose “overwrite to Primary Storyline”
then mine worked completely. No hassle.

I hope you too solve this problem. Hope this method work for you.