Silhouettes On Hidden Layer Objects in Blocks. A Bug?

The gif below shows the issue. The collection of objects is a block containing nested blocks the layers of which are hidden in the gif, so they disappear. But when the silhouette command is run, it draws silhouettes around them as if they were visible.

Hello - so far I only get silhouettes from visible block members - I guess I need to see an example setup, there are too many variables.