|Black media is offline.|
The black only showed as offline in the edit's view window / during playback of the edit. Opening the black in it's own view window worked just fine. Creating a new black filler didn't do any difference either. The solution is to add a title to the black, without adding any text. Afterwards the black will show up just fine. To me this seems to be a bug in Lightworks (I'm on version 11.1), as more people has reported it.
|add a title to the black filler|
|no text needed, just close the title window after deleting the default "Lightworks" title|
|Black is back online.|