Having issues making assemblies

[cstephens6Q5Y9]

I have several documents with components that I want to group into assemblies. I was able to create new components and drag and drop other components into them to make assemblies, except for a few of my files. Here's a screencast showing the issue.

https://autode.sk/3UupMwU

[TheCADWhisperer]

I don't understand the issue.

You have linked components.

Are you attempting to drag the linked components into the newly created local component?

If yes, what if you create that local component FIRST, make it Active and then drag and drop the linked components?